tag:blogger.com,1999:blog-3722233Mon, 28 Nov 2022 02:31:33 +0000typecastfocs metacommentsComputational ComplexityComputational Complexity and other fun stuff in math and computer science from Lance Fortnow and Bill Gasarchhttps://blog.computationalcomplexity.org/noreply@blogger.com (Lance Fortnow)Blogger2962125tag:blogger.com,1999:blog-3722233.post-5196164101457278361Mon, 21 Nov 2022 14:52:00 +00002022-11-21T08:52:16.363-06:00A Celebration of Juris<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxWze7urg3GUKNZRP8vI4maCWwNHi1JQkVcFCRfLas3dZQbmvYZz4jLurkuCXLAiLOFmKXjg7QAFHh5iNwt2vCR4ONgOSIHSBRpw1cC0rQjCvm9bKSSREiDMmPRLK8N3xtg9la8HCM7yr1iOTwP9v4FWv1eYhwGAQoF6JrbXlEZvw8LR-kug/s4080/PXL_20221104_140728676.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3072" data-original-width="4080" height="241" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxWze7urg3GUKNZRP8vI4maCWwNHi1JQkVcFCRfLas3dZQbmvYZz4jLurkuCXLAiLOFmKXjg7QAFHh5iNwt2vCR4ONgOSIHSBRpw1cC0rQjCvm9bKSSREiDMmPRLK8N3xtg9la8HCM7yr1iOTwP9v4FWv1eYhwGAQoF6JrbXlEZvw8LR-kug/s320/PXL_20221104_140728676.jpg" width="320" /></a></div><br />On November 4th I travelled to my undergraduate alma mater Cornell for a <a href="https://cis.cornell.edu/bowers-cis-community-celebrates-life-juris-hartmanis">Celebration of the Life and Career of Juris Hartmanis</a> who <a href="https://blog.computationalcomplexity.org/2022/08/the-godfather-of-complexity.html">passed away</a> in July. The workshop attracted many Cornell faculty and students, many of Hartmanis' former colleague and students, grad and undergrad, as well as his family. For the most part, the talks did not focus on technical content but rather memories of the great man. <p></p><p>I <a href="https://www.youtube.com/watch?v=ACxU-90O-ag&t=2768s">talked about</a> how Hartmanis founded the field of Computational Complexity and brought me into it. Herbert Lin <a href="https://www.youtube.com/watch?v=QKW_GalI31o&t=2900s">told the story</a> behind <a href="https://www.google.com/books/edition/Computing_the_Future/tYBQAAAAMAAJ">Computing the Future</a>, a 1992 agenda for the future of computer science led by Hartmanis and the challenge to the report by John McCarthy, one of the founders of AI. Should the agenda of computer science be solely in the hands of academic computer scientists, or should it take into account its role in the larger scientific and world-wide community? We still face these questions today.</p><p>Ryan Williams gave <a href="https://www.youtube.com/watch?v=ACxU-90O-ag&t=10350s">a powerful talk</a> about how Hartmanis personally intervened to ensure Ryan had a future in complexity. We are all better off for that.</p><p>After the workshop, Ryan and I walked around the campus and Collegetown reminiscing on how things have changed in the two decades since Ryan was an undergrad and the four decades (!) since I was. Most of the bars and restaurants have disappeared. The Arts quad is mostly the same, while the engineering building have been mostly rebuilt. There's a <a href="https://www.engineering.cornell.edu/magazine/features/gates-hall-new-home-cis">new computer science building</a> with <a href="https://ithacavoice.com/2022/05/cornell-plans-new-computer-science-building-on-hoy-field/">another on the way</a>. </p><p>I stayed in town to catch the Cornell football game the next day, as I once was on that field playing tuba for the marching band. They tore down the west stands to put up a parking lot and the east stands were sparsely filled watching Penn dominate the game.</p><p>Good bye Juris. You created a discipline, started one of the first CS departments, and plotted the future of both computational complexity and computer science as a whole. A master and commander indeed.</p>https://blog.computationalcomplexity.org/2022/11/a-celebration-of-juris.htmlnoreply@blogger.com (Lance Fortnow)1tag:blogger.com,1999:blog-3722233.post-1774067265916943204Thu, 17 Nov 2022 14:44:00 +00002022-11-17T08:44:08.549-06:00Fall Jobs Post 2022<p>In the fall I try to make my predictions on the faculty job market for the spring. The outlook this year is hazy as we have two forces pushing in opposite directions. </p><p>Most of the largest tech companies are having layoffs and hiring freezes amidst a recession, higher expenses and a drop in revenue from cloud and advertising. Meanwhile computing has never had a more exciting (or scary) year of advances, particularly in generative AI. I can't remember such a dichotomy in the past. In the downturn after the 2008 financial crisis computing wasn't particularly exciting as the cloud, smart phones and machine learning were then just nascent technologies.</p><p>We'll probably have more competition in the academic job market as many new PhDs may decide to look at academic positions because of limited opportunities in large tech companies. We might even see a reverse migration from industry to academia from those who now might see universities as a safe haven.</p><p>What about the students? Will they still come in droves driven by the excitement in computing or get scared off by the downturn in the tech industry. They shouldn't worry--the market should turn around by the time they graduate and even today there are plenty of tech jobs in smaller and midsize tech companies as well as companies that deal with data, which is pretty much every company.</p><p>But perception matters more than reality. If students do stay away that might reduce pressure to grow CS departments.</p><p>Onto my usual advice. Give yourself a good virtual face. Have a well-designed web page with access to all your job materials and papers. Maintain your Google Scholar page. Add yourself to the CRA's <a href="https://cra.org/cv-database/">CV database</a>. Find a way to stand out, perhaps a short video describing your research. </p><p>Best source for finding jobs are the ads from the <a href="https://cra.org/ads/">CRA</a> and the <a href="https://jobs.acm.org/">ACM</a>. For theoretical computer science specific postdoc and faculty positions check out <a href="https://cstheory-jobs.org/">TCS Jobs</a> and <a href="http://dmatheorynet.blogspot.com/">Theory Announcements</a>. If you have jobs to announce, please post to the above and/or feel free to leave a comment on this post. Even if you don't see an ad for a specific school they may still be hiring, check out their website or email someone at the department. You'll never know if you don't ask.</p>https://blog.computationalcomplexity.org/2022/11/fall-jobs-post-2022.htmlnoreply@blogger.com (Lance Fortnow)5tag:blogger.com,1999:blog-3722233.post-2374034479146058976Tue, 15 Nov 2022 04:18:00 +00002022-11-15T22:44:01.012-06:00Who first thought of the notion of Polynomial Time? <p>(Updated version of <i>Computational Intractability: A Guide to Algorithmic Lower Bound</i> by Demaine-Gasarch-Hajiaghayi is <a href="https://hardness.mit.edu/">here</a>)</p><p><br /></p><p>Any question like <i>who first though of X </i>is often hard to answer. I blogged about who first came up with the Fib numbers <a href="https://blog.computationalcomplexity.org/search?q=Fib">here</a>. I've heard rumors that IBM had search engines way before Google but could not figure out how to make money off of it. There are other examples. </p><p>I had learned that Cobham defined P in the paper <i>The intrinsic computational difficulty of functions</i>, in 1965. It was The conference on Logic, Methodology, and Philosophy of Science. The paper is <a href="https://www.cs.toronto.edu/~sacook/homepage/cobham_intrinsic.pdf">here</a>. Jack Edmonds had the notion of P in the paper <i>Paths, Trees, and Flowers <a href="https://math.nist.gov/~JBernal/p_t_f.pdf">here</a> </i>in 1965.</p><p>While it is true that Cobham defined P in that paper, and he might have been the first one to do so, was the notion somehow around earlier. I first thought the answer was no. Why? Because if you look at Joe Kruskal's paper on MST (see <a href="https://www.ams.org/journals/proc/1956-007-01/S0002-9939-1956-0078686-7/S0002-9939-1956-0078686-7.pdf">here</a>) you don't see anything resembling time complexity. No O(E+Vlog V) or whatnot. So I thought that if the notion of <i>this algorithm runs in such-and-such time </i>was not in the air, then certainly any notion of P could not have been. </p><p>Hence I was surprised when I accidentally (more on that later) came across the following: </p><p>In 1910 (really, 1910) H.C.Pocklington analyzed two algorithms for solving quadratic congruences and noticed that </p><p><i>one took time proportional to a power of the log of the modulus, where as</i></p><p><i>the other took time proportional to the modulus itself or its square root. </i></p><p>THAT is the distinction between P and NOT-P. </p><p>The paper is titled <i>The determination of the exponent to which a number belongs, the practical solution of</i> <i>certain congruences, and the law of quadratic reciprocity. </i>It appeared in 1910, in the Proceedings of the Cambridge Philosophical Society, Volume 16, pages 1-5. (I could not find it online. If you know of a place online for it, leave a comment.) </p><p>ADDED LATER: Here is the article in pieces: <a href="https://www.cs.umd.edu/~gasarch/BLOGPAPERS/pockpage1.png">Page 1</a>, <a href="https://www.cs.umd.edu/~gasarch/BLOGPAPERS/pockpage2,3.png">Pages2,3</a>, <a href="https://www.cs.umd.edu/~gasarch/BLOGPAPERS/pockpage4,5.png">Pages4,5</a>.</p><p>How did I come across this? And why had I NOT come across this in my roughly 40 years working in complexity theory? </p><p>I came across it while reading a blog of Scotts, <i>The Kolmogorov Option, </i>see <a href="https://scottaaronson.blog/?p=3376">here</a> where Pocklington is mentioned in passing. I am surprised how arbitrary the set of things ones knows can be. I have put the Pocklington story in the Demaine-Gasarch-Hajiaghayi book <a href="https://hardness.mit.edu/">Computational Intractability: A Guide to Algorithmic Lower Bounds</a> so that this knowledge gets to be better known.</p><p>ADDED LATER: That Cobham and Edmonds are known for discovering or inventing P is an example of the well known </p><p><b>Columbus Principle</b>: Things are named after the LAST person to discover them (note that Columbus was the last person to discover America.)</p><p>Bonus Question: Most principles where the author is not on it, the author might be unknown. NOT in this case. I KNOW who coined the term `Columbus Principle' Do you? (It was not me.) </p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p>https://blog.computationalcomplexity.org/2022/11/who-first-thought-of-notion-of.htmlnoreply@blogger.com (gasarch)13tag:blogger.com,1999:blog-3722233.post-3299749567675625592Thu, 10 Nov 2022 15:21:00 +00002022-11-11T11:24:44.445-06:00The Structure of Data and Machine Learning<p>Terry Tao entitled his <a href="https://www.youtube.com/watch?v=XWF1BuJ0Sfc">2006 Fields Medal Lecture</a> "The Dichotomy between structure and randomness" and state the Structure Theorem: Every object is a superposition of structured object and a pseudorandom error. He gave many examples and how he used these results to prove (with Ben Green) that the primes contain arbitrarily long linear progressions.<br /></p><p>There is a nice Kolmogorov interpretation. Recall K(x) is the smallest program that produces the string x. For a finite set S, K(S) is the smallest program that recognizes membership in S. For a string x, take the largest set S containing x such that K(x) is close to K(S) + log(|S|). S is the structure and x is a random element of S. Vereshchagin and Vitanyi have a <a href="https://doi.org/10.1109/TIT.2004.838346">nice paper</a> on this topic.</p><p>Machine learning aims to discover the set S from a set of examples x. This is why I think of P = NP giving us an ideal machine learning algorithms--use P = NP to find a circuit that describes S for a time-bounded version of Kolmogorov complexity. Recent tools in machine learning seem to find this S without needing the full power of P = NP.</p><p>Consider languages where German or Japanese is a random example of a "natural language". Linguistics tries to understand the structure of natural languages. Recent <a href="https://about.fb.com/news/2020/10/first-multilingual-machine-translation-model/">ML translations algorithms</a> use that structure (without understanding it) to translate between pairs of languages. </p><p>How about generative AI? Diffusion methods create a set S of all reasonable images by turning images into random noise. To create images it reverses that process, starting with random noise to create random elements of S. Prompts just add conditions to the process.</p><p>I read the Vereschagin-Vitanyi paper back in 2004 and the Kolmogorov structure model goes back to the 1970s. Finding the structure seemed intractable for any interesting application. Now that ML is proving this wrong, the world is a different place.</p>https://blog.computationalcomplexity.org/2022/11/the-structure-of-data-and-machine.htmlnoreply@blogger.com (Lance Fortnow)3tag:blogger.com,1999:blog-3722233.post-2825192225910381396Tue, 08 Nov 2022 00:43:00 +00002022-11-07T18:43:52.908-06:00Euclidean TSP is NP-hard but not known to be in NP. Why not known?<p>BILL: Lance, I was looking into TSP, metric TSP, Euclidean TSP since I am going to teach about P, NP, NPC, and approximating NPC problems and I came across the following from Lipton's book <i>The P=NP</i> <i>Question and Godel's Letter (</i>I paraphrase<i>):</i></p><p>Graham proved that Euclidean TSP was NP-hard. But it is open if it is in NP. The difficulty hinges on a beautiful problem that is still open over thirty years later: Can we tell, given naturals a1,...,an,k if</p><p><br /></p><p>\sqrt{a1} + ... + \sqrt{an} \le k</p><p>What I want to know is, is it still open? Lipton's book was written in 2010, so that was. uh, uh...</p><p>LANCE: 11 years ago.</p><p>BILL: Which is a long time ago- so has it been cracked?</p><p>LANCE: No it has not. And, by the way, I blogged on it <a href="https://blog.computationalcomplexity.org/2003/02/traveling-salesman-on-plane.html">in 2003</a>.</p><p><br /></p><p>This raises some questions:</p><p>1) Is the sqrt problem above in P? NP? (I have seen it stated that the problem is in PSPACE.) </p><p>2) Where do people think the problem is?</p><p>3) Why is it still open? Some options (I am sure there are more.)</p><p>a) Not that many people are working on it. But if not, why not?</p><p>b) The problem is just dang hard! That's probably why P vs NP is still unsolved and why FLT took so long, and why my proof of the Riemann hypothesis was so long in coming.) I am reminded of Erdos' quote on The Collatz Conjecture: <i>Mathematics may not be ready for such problems. </i>And you all know what Erdos said about R(5). </p><p>c) Reasons a and b above may lead to a death spiral: People THINK its hard so they don't work on it, then since nobody works on it no progress is made, reinforcing that its hard. </p><p><br /></p><p><br /></p>https://blog.computationalcomplexity.org/2022/11/euclidean-tsp-is-np-hard-but-not-known.htmlnoreply@blogger.com (gasarch)9tag:blogger.com,1999:blog-3722233.post-1022697361105747430Thu, 03 Nov 2022 12:18:00 +00002022-11-03T07:23:10.244-05:00Should you quit Twitter and Texas?<p>Generally with some exceptions, I use <a href="https://facebook.com/fortnow">Facebook</a> for personal stuff, <a href="https://www.linkedin.com/in/fortnow/">LinkedIn</a> for Illinois Tech stuff and <a href="https://twitter.com/fortnow">Twitter</a> and this blog for CS stuff. Many of you got to this post through the <a href="https://twitter.com/fortnow/status/1588144625755328514">Twitter link</a>. Now that Elon Musk has bought the social media company, should I and the rest of the academic twitterverse move on to something else?</p><p>I'd say not yet. Let's see what Elon does to the place. Maybe he can allow more points of view, without turning it into a cesspool. Or maybe he ruins it. It'll be a network effect--if too many academics leave Twitter, I'd have to follow or I'd have few followers. I wonder where they will go. I hope it isn't TikTok.</p><p>On a similar vein, I often here of those who suggest we don't hold conferences in certain jurisdictions for political reasons, for example Texas, because of its laws against abortion and transgender rights. I don't believe computer science, as a field, should be making decisions based on politics. Academics who live in these states don't generally hold the same views as the political leaders in those states.</p><p>Should we not have meetings in Illinois because some in our field might be opposed to abortion? Or do we just assume everyone has the same political views in the field. Individuals can make their own choices as to whether to attend, but it's best when politics is left out of academics. <a href="https://focs2022.eecs.berkeley.edu/">FOCS 2022</a> is wrapping up today in Denver. Seems like a safe choice--perhaps all US conferences in the future should be in Colorado. </p><p>There are limits--I wouldn't attend or organize a conference in Russia in the near future. But if we start eliminating locations based on politics, we'll only be able to meet up in the metaverse, and we won't have social media to tell us how to get there.</p>https://blog.computationalcomplexity.org/2022/11/should-you-quit-twitter-and-texas.htmlnoreply@blogger.com (Lance Fortnow)39tag:blogger.com,1999:blog-3722233.post-495471484673519962Sun, 30 Oct 2022 17:35:00 +00002022-10-30T20:21:54.817-05:00What was the recent Nobel Prize in Physics really about?(Guest Post) <p> David Marcus was a Math major a year ahead of me at SUNY Stony brook (he graduated in 1979,</p><p>I graduated in 1980). He then got a PhD from MIT in Math, and is a reader of this blog. Recently he emailed me that he thinks the current Nobel Prize Winners in Physics do not understand their own work. Is it true? Let's find out!</p><p>------------------------</p><p>(Guest blog from David Marcus)</p><p>2022 Nobel Prize in Physics Awarded for Experiments that Demonstrate Nonlocality</p><p>The 2022 Nobel Prize in Physics was recently awarded to experimenters who demonstrated that the world is nonlocal. The curious thing is that neither the writers of the Nobel Prize press release nor the recipients seem to understand that this is what they demonstrated.</p><p><br /></p><p>For example, the press release (see <a href="https://www.nobelprize.org/prizes/physics/2022/press-release/">here</a>) says: "John Clauser developed John Bell's ideas, leading to a practical experiment. When he took the measurements, they supported quantum mechanics by clearly violating a Bell inequality. This means that quantum mechanics cannot be replaced by a theory that uses hidden variables." That is not what the experiments mean, and the statement is false.</p><p>The word "locality" means that doing something here cannot instantly change something other there.</p><p>The experimental setup is the following: You prepare two particles, A and B, and send them in opposite directions so that they are far apart. You and your colleague do experiments on each particle at the same time. If you and your colleague perform the same experiment, then, from your experiment on A, you can predict with certainty the result of your colleague's experiment on B (and vice versa).</p><p>In a paper in 1935, Einstein, Podolsky, and Rosen pointed out that, assuming locality, the experimental results at A and B must be determined by the source that prepared the particles. They didn't actually say, "assuming locality", but they implicitly assumed it. (If you disagree with them, please offer an alternative.)</p><p>In 1964, John Bell published his paper. In it, he considered three of the experiments that could be done on the particles A and B. Assuming the results are determined by the source (which follows from Einstein, Podolsky, and Rosen's argument), he derived an inequality on the correlations between the results of the three experiments on the two particles. The math is simple; for details, see <a href="http://www.scholarpedia.org/article/Bell%27s_theorem">here</a>.</p><p>The Nobel Prize winners did experiments, and their results violated Bell's inequality (or similar inequalities). Hence, the world is nonlocal.</p><p>The simplest theory that agrees with experiment is Bohmian Mechanics. This is a deterministic theory of particles whose motion is governed by a wave (the wave function being the solution of the Schrödinger equation). Of course, Bohmian Mechanics is nonlocal, as is the world.</p>https://blog.computationalcomplexity.org/2022/10/does-physics-nobel-prize-winner.htmlnoreply@blogger.com (gasarch)62tag:blogger.com,1999:blog-3722233.post-1651627557165337483Thu, 27 Oct 2022 11:46:00 +00002022-10-27T11:03:13.288-05:00The Media Coverage of the Matrix result is Terrible (though not worse than usual)<p> BILL: A computer program (or an AI or an ML or whatever) found a BETTER way to do matrix mult! Its in the same spirit as Strassen. I've always wondered if Strassen was practical since it is simple, and computers have come a long way since 1969, though I suspect not (I WAS WRONG ABOUT THAT). I'll blog about and ask if Strassen will ever be used/practical (I did that post <a href="https://blog.computationalcomplexity.org/2022/10/will-strassens-matrix-mult-alg-ever-be.html">here</a>).</p><p>READERS: Uh, Bill, (1) Strassen IS used and practical and (2) the new algorithm only works in GF(2). (Lance did a post about the new algorithm where he makes this explicit <a href="https://blog.computationalcomplexity.org/2022/10/alpha-tensor.html">here</a>.) Some readers claimed it was GF(2^k) and some that it was fields if char 2. In any case NO it is not a general algorithm.</p><p>BILL: There is good news and what others might consider bad news but I do not.</p><p>GOOD NEWS: I learned that Strassen IS practical and used, which I did not know. </p><p>GOOD NEWS: I learned that I was WRONG about the new algorithm since I just assumed it worked in general, and updated the post so others would not be deceived. </p><p>BAD NEWS: Darling asked if I was embarrassed to be wrong. If I am embarrassed that easily I would have quit blogging in 2009. </p><p>DARLING: So Bill, how did you get it so wrong?</p><p>BILL: Well obviously my bad for not doing my due diligence. But that's not what's interesting. What's interesting is that if you read the articles about it for the popular press you would have NO IDEA that it only works for mod 2. Its like reading that quantum computing will solve world hunger.</p><p>DARLING: It won't?</p><p>BILL: No it won't. </p><p>DARLING: I was being sarcastic. </p><p>BILL: Anyway, the coverage pushed two points</p><p>a) IMPRESSIVE that a computer could FIND these things that humans could not. This is TRUE (gee, how do I know that? <i>The Gell-Mann Effec</i>t, is that people disgusted when they read a newspaper article on something they know about and find the mistakes later assume that the other articles are fine. SHOUT OUT to Jim Hefferon who telling me the name <i>Gell-Mann Effect</i> and left a comment with a pointer. The original version of this post had a BLANK there.) </p><p>b) The algorithm is practical! They did not quite say that but it was implied. And certainly there was NO mention of it only working in GF(2). And I was fooled into thinking that it might be competitive with Strassen. </p><p>READERS (of this blog entry, I predict) Uh, Bill, the popular press getting science news wrong and saying its more practical than it is probably predates the Bible. I can imagine the Cairo Times in 2000BC writing <i>`Scientists discover that in any right triangle with sides a,b,c a^2+b^2=c^2 and this will</i> <i>enable us to build food silos and cure Hunger</i>. In reality they knew that the 3,4,5 triangle was a right triangle, were no where near a proof of a general theorem, and I doubt it would have helped cure hunger. </p><p>BILL: This time the news was REALLY CLOSE to what I do (if R(5) is found by a computer and the media claims its practical I'll either have a very angry blog or repost my April Fools' day article on Ramsey Theory's application to History) AND I posted incorrectly about it. So, to quote many a bad movie</p><p><b>THIS TIME ITS PERSONAL!</b></p>https://blog.computationalcomplexity.org/2022/10/the-media-coverage-of-matrix-result-is.htmlnoreply@blogger.com (gasarch)7tag:blogger.com,1999:blog-3722233.post-234916787051478396Mon, 24 Oct 2022 14:04:00 +00002022-10-24T09:04:39.838-05:00Cheating in Chess and in Class<p>In the 24th move of the second game of the 1978 Chess Championship, a cup of blueberry yogurt was delivered to the defending champion Anatoly Karpov who offered a draw shortly thereafter. The challenger Victor Korchnoi claimed the flavor of yogurt was a coded message to Karpov and later in the tournament all food deliveries had to be decided on in advance. The good old days.</p><p>With computer chess programs now far more powerful than humans, chess cheating has become far more common and came to a head last month with the controversy between <a href="https://en.wikipedia.org/wiki/Carlsen%E2%80%93Niemann_controversy">Magnus Carlsen and Hans Niemann</a>. Did Niemann cheat to win in his win over Carlsen in St. Louis or was it just a rare upset? How can we tell?</p><p>This brings up cheating by students in class. <a href="https://www.npr.org/2021/08/27/1031255390/reports-of-cheating-at-colleges-soar-during-the-pandemic">Reports</a> and <a href="https://academicintegrity.org/resources/facts-and-statistics">statistics</a> show that cheating has increased over the last few years. The pandemic played a role, but a good rule is that pandemic didn't change behaviors, rather accelerated changes already in progress. Technology has made it easier to cheat. It's difficult to near impossible to create a homework problem where someone couldn't just look up an answer. Sites like Chegg provide solutions to all sorts of problems while there are many sites where you can hire someone to write a paper or do a project for you. Advances in generative AI, like GPT-3 and GitHub co-pilot will soon make cheating as easy as clicking a button.</p><p>But it's more than technology. As students view university education less about learning and more about getting the credentials for a job, the inhibitions to cheat disappear. And while the vast majority of students don't significantly cheat, it's hard for anyone to avoid using Google when they get stuck on a problem. </p><p>We can continue to use technology to fight the technology in a every growing arms race to catch cheaters but it can feel like a losing war. We should take solace that the students who work hard solving problems and projects will be the ones who will succeed in life. </p>https://blog.computationalcomplexity.org/2022/10/cheating-in-chess-and-in-class.htmlnoreply@blogger.com (Lance Fortnow)2tag:blogger.com,1999:blog-3722233.post-7404772395411010832Thu, 20 Oct 2022 14:27:00 +00002022-10-20T09:29:15.907-05:00Alpha Tensor<p>In a <a href="https://blog.computationalcomplexity.org/2022/10/will-strassens-matrix-mult-alg-ever-be.html">recent post</a>, Bill used the announcement of a new AI multiplication algorithm to discuss the applications of Strassen's famous algorithm. For this post I'd like to focus on the new algorithm itself, <a href="https://www.deepmind.com/blog/discovering-novel-algorithms-with-alphatensor">Alpha Tensor</a>, the algorithm behind the algorithm, what it has actually accomplished and what it means for us theorists. </p><p>To multiply two 2x2 matrices in the usual way you need eight multiplication steps. In 1969 Strassen surprised the world by showing how to <a href="https://en.wikipedia.org/wiki/Strassen_algorithm#Algorithm">multiply those matrices using only seven multiplications</a>.</p><p>You can recurse on larger matrices. For 4x4 matrices you can use 7<sup>2</sup>=49 multiplications instead of the naïve 64. In general for nxn matrices you need roughly n<sup>log<sub>2</sub>7</sup> ≈ n<sup>2.81</sup> multiplications.</p><p>No one has found an algorithm for 4x4 matrices that uses less than 49 from recursing on Strassen. Alpha Tensor does so for the special case of working over GF[2], where addition and subtraction are interchangeable. Their algorithm does not work for general fields such as the real numbers.</p><p>Here's the full table of Alpha Tensor results from the <a href="https://doi.org/10.1038/s41586-022-05172-4">Nature paper</a> for multiplying a nxm matrix by a mxp matrix. The Modular column is for GF[2] and the standard column is for general fields. Alpha tensor does improve on the best known for general fields for specific problems like multiplying a 3x4 matrix by a 4x5 matrix. Much of the press <a href="https://arstechnica.com/information-technology/2022/10/deepmind-breaks-50-year-math-record-using-ai-new-record-falls-a-week-later/">failed to make this distinction</a> for 4x4 multiplication leading to some confusion.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9-_aNBNNDkLCuUrz9Wz2dzgctRxEAk2Q8ptCHuk1SwBLyNrwentWYhpYulJX3VP64GE3UxlfaQlSHxm2faVnrh44MCnEyHSM2o-998w6P0_gKIk9fPScLQU9PtxKUPmfuFZR6SiYYlvuXw01FhP0Jg24ro1j0YCY99pxg7aTzMI7mzgWCfw/s833/IMG_0190.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="833" data-original-width="702" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9-_aNBNNDkLCuUrz9Wz2dzgctRxEAk2Q8ptCHuk1SwBLyNrwentWYhpYulJX3VP64GE3UxlfaQlSHxm2faVnrh44MCnEyHSM2o-998w6P0_gKIk9fPScLQU9PtxKUPmfuFZR6SiYYlvuXw01FhP0Jg24ro1j0YCY99pxg7aTzMI7mzgWCfw/w540-h640/IMG_0190.jpg" width="540" /></a></div><br /><div class="separator" style="clear: both; text-align: left;">What does this mean for theory? Recursing on 4x4 matrices now reduces the time for matrix multiplication to roughly n<sup>2.78</sup> nowhere close to the best <a href="https://doi.org/10.1137/1.9781611976465.32">theoretical upper bound</a> of about n<sup>2.37</sup>. The Alpha tensor result may be more practical though time will tell.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">Manuel Kauers and Jakob Moosbauer shortly after Alpha Tensor announcement, <a href="https://arxiv.org/abs/2210.04045">reduced</a> the 5x5 case over GF[2] to 95 multiplications. Nice to see the last word isn't by machine (yet!) but that shouldn't reduce the excitement over Alpha Tensor. Often we see a breakthrough followed by a small improvement. Note that 95 multiplications for 5x5 matrices won't give a faster asymptotic algorithm for nxn multiplication than Strassen.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">What excites me the most is not the algorithm, but the algorithm to find the algorithm. Alpha Tensor uses the tools that AlphaZero used to play Chess and Go to search the large search space of potential algorithms using Monte Carlo Tree search, basically searching at random and learning and updating the probabilities of the search. Before using machine learning, we had few good approaches to searching large combinatorial spaces of this nature. </div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">In general, most new algorithms come from new approaches, not just from the structural decomposition we see in matrix multiplication so theorists won't be out of a job anytime soon. Nevertheless this is just another lesson that using ML has dramatically improved our ability to search through a large number of possibilities looking for a specific solution. </div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">The Alpha Tensor Nature paper was <a href="https://www.nature.com/articles/s41586-022-05172-4#article-info">submitted</a> in October of 2021. A year is eternity in the ML world. I wonder what is happening now that we don't know about.</div>https://blog.computationalcomplexity.org/2022/10/alpha-tensor.htmlnoreply@blogger.com (Lance Fortnow)6tag:blogger.com,1999:blog-3722233.post-7730662860220569597Tue, 18 Oct 2022 06:02:00 +00002022-10-18T01:02:19.003-05:00BYTE LYNX- an awesome video game/Am I an influencer?<p><br /></p><p>Tucker Bane is a friend of mine who has an AWESOME video game available</p><p>that is called BYTE LYNX.</p><p>I am curious- Can I be an INFLUENCER!</p><p>Lets find out!</p><p><br /></p><p>At the link below there are</p><p><br /></p><p>a) Reviews of the game.</p><p>b) Videos of the game being played.</p><p>c) The ability to purchase and download the game.</p><p><br /></p><p>Link is <a href="https://store.steampowered.com/app/1996600/Byte_Lynx/">here</a></p><p><br /></p><p><br /></p>https://blog.computationalcomplexity.org/2022/10/byte-lynx-awesome-video-gameam-i.htmlnoreply@blogger.com (gasarch)2tag:blogger.com,1999:blog-3722233.post-892869288985190689Thu, 13 Oct 2022 13:34:00 +00002022-10-16T10:00:10.933-05:00How Not to Pass a Polygraph Test<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbVRkVbxq4nkOBNugqs01If78vjWowLhCCowXwEXkJCHuST_xZVWQApkTScjld0Z8sDgxwU_R6AwWsKPB4gbiKYW--3TkWtcpZGV4N2skRt7tW2XvxBi5VRjWQKZcqigp8Ewp18q6MrZQUUq_Y09300z8muVgiVskef70PibPTlUGGb08V_w/s300/meet-the-parents-original-300x189.jpg" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="189" data-original-width="300" height="189" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbVRkVbxq4nkOBNugqs01If78vjWowLhCCowXwEXkJCHuST_xZVWQApkTScjld0Z8sDgxwU_R6AwWsKPB4gbiKYW--3TkWtcpZGV4N2skRt7tW2XvxBi5VRjWQKZcqigp8Ewp18q6MrZQUUq_Y09300z8muVgiVskef70PibPTlUGGb08V_w/s1600/meet-the-parents-original-300x189.jpg" width="300" /></a></div><br />Many years ago I was asked to serve on an advisory board for an organization that did confidential research. To be on the board I had to have US top secret clearance. The first step was filling out a lengthy form which asked deep details about every aspect of my life. Then there were the interviews with myself and many people I interacted with, especially internationally, and I have many international colleagues. Eventually I got past these steps.<div><br /></div><div>The final step required taking a polygraph (lie-detector) test. So I flew to Baltimore to visit a non-descript office building near the airport. I failed the test. Twice more I went to Baltimore and failed those tests as well. </div><div><br /></div><div>Just to be clear, I never tried to falsify or hide information on these tests. In one case I was asked "Do you live in Atlanta?" I said no. The person administering the test stopped and said I put my address down as Atlanta. I said my mailing address was Atlanta but (at the time) I lived just north of the border in Sandy Springs. She said I should use Atlanta for the test, in other words I should lie. The test didn't go well after that.</div><div><br /></div><div>In another case, I was asked if I was ever arrested. For the record, I have never been arrested but the answer came up as inconclusive. The administrator, different than before, trusted the machine more than me and the rest of the day didn't go well. </div><div><br /></div><div>Perhaps the test wasn't meant to just test whether I was telling the truth, but also my ability to keep a secret. At least that would make more sense why I failed three times. More likely I took questions too literally, a product of a mathematician's mind.</div><div><br /></div><div>I never joined the advisory board but that wasn't the worst of it. In 2014 the Chinese hacked into the US Office of Personnel Management taking information from, among others, those who applied for security clearance. It's the main reason I keep security freezes with the credit bureaus.</div>https://blog.computationalcomplexity.org/2022/10/how-not-to-pass-polygraph-test.htmlnoreply@blogger.com (Lance Fortnow)6tag:blogger.com,1999:blog-3722233.post-8978327258415406646Mon, 10 Oct 2022 04:03:00 +00002022-10-14T09:15:23.340-05:00Will Strassen's Matrix Mult Alg ever be practical? <p>All time bounds are asymptotic and really O-of.</p><p>Recall that Strassen found a clever way to multiply two 2x2 matrices with 7 mults (and lots of adds) leading to a matrix mult alg in n^{\log_2 7} = n^{2.87...}</p><p><br /></p><p>Recently (see <a href="https://www.newscientist.com/article/2340343-deepmind-ai-finds-new-way-to-multiply-numbers-and-speed-up-computers/">here</a>) a deep-mind-AI found a way to multiply two 4x4 matrices with 47 mults (and lots of adds) leading to a matrix mult alg in n^{\log_4 47} = n^{2.777...}. NOTE ADDED: The new algorithm only works over GF[2] for 4x4 matrices.</p><p>Much better is known, see our blog posts <a href="https://blog.computationalcomplexity.org/2011/11/matrix-mult-you-heard-it-here-third.html">here</a> and <a href="https://blog.computationalcomplexity.org/2015/06/when-do-we-care-about-small-improvements.html">here</a>.</p><p><br /></p><p>The more advanced algorithms are complicated and have large constants so will never be practical. But Strassen's result, and now the new algorithm, SEEM to me they could be practical.</p><p>(ADDED LATER- many of the comments inform me that Strassen IS practical and IS being used. Great! Now we know!)</p><p>Thoughts about Strassen that also apply to the new algorithm. </p><p>1) n has to be large for Strassen to given an improvement. But as we deal with larger data sets the value of n is getting larger. </p><p>2) People are mostly interested in sparse matrices for which there are better methods. I've heard that for a while- but is it still true? I thought ML used dense matrices. </p><p>3) Strassen is hard to code up. Actually it doesn't look that hard to code up. However, I have never tried to code it up, so maybe there are subtle points there.</p><p>4) Strassen only works on matrices of size 2^n x 2^n. You can pad matrices out but that might kill whatever time advantage you get. (The new alg only works on 4^n x 4^n). </p><p>5) Strassen uses recursion and there is <i>the hidden cost of recursion</i>. I think that is a think of the past and our younger readers do not know what I am talking about. </p><p>6) (This is obvious) the recursion would only go down to a certain level and THEN you would use ordinary Matrix Mult. This may also add time. </p><p><br /></p><p>I suspect that 2 and 4 are the most important reasons Strassen (or the new algorithm) is not practical BUT I would like to hear your thoughts?</p><p>Does any package NOW use Strassen's Algorithm?</p><p>Side Note: I like to ask students if they think there is a better-than-cubic algorithm for Matrix Mult. They do not. Then I show it to them and tell them THIS is why LOWER BOUNDS are hard. You have to show that NO, nobody clever will find a trick you hadn't thought of. </p><p><br /></p>https://blog.computationalcomplexity.org/2022/10/will-strassens-matrix-mult-alg-ever-be.htmlnoreply@blogger.com (gasarch)16tag:blogger.com,1999:blog-3722233.post-6131043346672536750Thu, 06 Oct 2022 13:40:00 +00002022-10-06T08:40:17.922-05:00Art and Technology<p>Last weekend I went to one of Chicago's jewels, the Art Institute, and saw the opening of a new exhibit by Berlin-based artist Josephine Pryde entitled <a href="https://www.artic.edu/exhibitions/2932/the-vibrating-slab">The Vibrating Slab</a> referring mainly to the phone that constantly tries to gain our attention. The exhibit used photographs and sculptures to tie smart phones to prehistoric rocks. No pictures here because ironically they didn't allow us to take photos with our "slabs".</p><p>After I saw the Pryde exhibit I went to see the artist herself give a presentation. She related a story where she talked about going to the movies and seeing <a href="https://www.imdb.com/title/tt1745960">Top Gun: Maverick</a>, not knowing it is a new release. Tom Cruise, who <a href="https://www.youtube.com/watch?v=PJqbivkm0Ms">controlled a computer with hand movements</a> in Minority Report, goes old-school in Maverick. Cruise and several young actors, through various plot contrivances, flew 20th century planes in a movie that could have taken place in the 90s. According to IMBD, at the insistence of Tom Cruise, minimal green screen and CGI aerial shots exist in the film, and even the close up cockpit shots were taken during real in-flight sequences. Old school indeed. Kind of the opposite of say the Disney series <a href="https://www.imdb.com/title/tt8111088/">The Mandalorian</a> filmed in a soundstage with everything generated by CGI.</p><p>Pryde's exhibit looked at the interaction with technology as art. Upstairs from Pryde's exhibit was art from technology, a <a href="https://www.artic.edu/exhibitions/9705/david-hockney-the-arrival-of-spring-normandy-2020">series of prints</a> that David Hockney created on another slab, the iPad, in Normandy during the early days of the Covid pandemic. </p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://artic-web.imgix.net/b8c0f3d0-2abc-4c17-9aba-629d8536e90d/IPD-2221.jpg?rect=0%2C0%2C3564%2C2490&auto=format%2Ccompress&q=80&fit=crop&crop=faces%2Cedges%2Centropy&w=1600&h=1118" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="559" data-original-width="800" height="280" src="https://artic-web.imgix.net/b8c0f3d0-2abc-4c17-9aba-629d8536e90d/IPD-2221.jpg?rect=0%2C0%2C3564%2C2490&auto=format%2Ccompress&q=80&fit=crop&crop=faces%2Cedges%2Centropy&w=1600&h=1118" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">No. 340, 21st May 2020 - David Hockney</td></tr></tbody></table><div><p>On the way from Pryde's exhibit to the lecture I passed through the Art Institute's impressionism collection and compared real Monets with the fake one I created with Dall-E. Monet manages to capture a detailed scene with broad brush strokes--if you zoom in the detail disappears. Dall-E can't quite pull that off.</p><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://www.artic.edu/iiif/2/d39b1026-7d8d-6e6a-738e-8a136b1a0033/full/843,/0/default.jpg" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="770" data-original-width="800" height="308" src="https://www.artic.edu/iiif/2/d39b1026-7d8d-6e6a-738e-8a136b1a0033/full/843,/0/default.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><a href="https://www.artic.edu/artworks/14634/vetheuil">Vétheuil</a> by Monet<br /><br /></td></tr></tbody></table><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ6-EWvauVOODiC3Q6NtPqk34MFd8yF-m0Pr8qms48vtunPrdnclEYpSdFnlm691u7vTf4qU7EkPCOSaY8NSmfxh6FYsgKUN5QWaAzirVQDaX_Y9kZarqcyCtUafapja3KIy3k6bUd9SrlL83yCOnayQgseDMD3xcCwfPzvb0kimeKIr8FDw/s1024/DALL%C2%B7E%202022-09-17%2014.00.36%20-%20Schloss%20Dagstuhl%20in%20the%20style%20of%20monet.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1024" data-original-width="1024" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ6-EWvauVOODiC3Q6NtPqk34MFd8yF-m0Pr8qms48vtunPrdnclEYpSdFnlm691u7vTf4qU7EkPCOSaY8NSmfxh6FYsgKUN5QWaAzirVQDaX_Y9kZarqcyCtUafapja3KIy3k6bUd9SrlL83yCOnayQgseDMD3xcCwfPzvb0kimeKIr8FDw/w320-h320/DALL%C2%B7E%202022-09-17%2014.00.36%20-%20Schloss%20Dagstuhl%20in%20the%20style%20of%20monet.png" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Monet Dagsthul by Dall-E</td></tr></tbody></table><p><br /></p></div>https://blog.computationalcomplexity.org/2022/10/art-and-technology.htmlnoreply@blogger.com (Lance Fortnow)4tag:blogger.com,1999:blog-3722233.post-7262081120052063822Tue, 04 Oct 2022 14:05:00 +00002022-10-04T09:05:09.939-05:00Is it okay for a paper or book to say `for more on this topic see Wikipedia Entry BLAH. <p> One of the proofreaders for <i>Computational Intractability: A Guide to Algorithmic Lower Bounds</i></p><p>(available <a href="https://hardness.mit.edu/">here</a>)</p><p>made the following objection, which raises some questions.</p><p><i>I object to telling readers to see a Wikipedia Entry. Wikipedia is marvelous, but it is unstable. I have been led astray by short-lived editorial changes made by trolls. </i></p><p>The proofreader is surely correct that `See Wikipedia entry X' should be minimized. And indeed, I have gone through all of the cases we had of such things and tried to minimize them. But there are times when there seems to be no way around it. Or maybe there is but I can't see it. </p><p>a) I want to refer to the set of problems that are (exists R)-complete. The ONLY list I know of is on Wikipedia <a href="https://en.wikipedia.org/wiki/Existential_theory_of_the_reals">here</a>.</p><p>b) I want to discuss the complexity of the video game braid. There is a nice Wikipedia page about the game braid <a href="https://en.wikipedia.org/wiki/Braid_(video_game)">here</a>. There are some sites that have videos about the game, but not reallyan explanations of it. I DID find a site that looks pretty good, <a href="https://strategywiki.org/wiki/Braid">here</a>, but is that site more stable than the Wikipedia entry? There did not seem to be an official site. (I had the same issue with<a href="https://en.wikipedia.org/wiki/15_puzzle"> the 15-puzzle</a> and some other puzzles that do not seem to have a natural official site). </p><p>c) I want to refer the reader to a list of algorithms for discrete log. Wikipedia has a great site on this <a href="https://en.wikipedia.org/wiki/Discrete_logarithm">here</a>. Is there a good article that does the same? Is it behind paywalls?</p><p><br /></p><p>I tend to thing that the Wikipedia sites above are stable and accurate. It helps that they are not on controversial topics. They should be fine. Articles that are behind paywalls are much worse. As for articles on authors websites- are they more or less stable than Wikipedia?</p><p><br /></p><p><br /></p><p><i><br /></i></p><p><br /></p><p><span face="Arial, Helvetica, sans-serif" style="background-color: white; color: #222222; font-size: small;"><br /></span></p><p><br /></p>https://blog.computationalcomplexity.org/2022/10/is-it-okay-for-paper-or-book-to-say-for.htmlnoreply@blogger.com (gasarch)6tag:blogger.com,1999:blog-3722233.post-140442697667456694Thu, 29 Sep 2022 14:35:00 +00002022-09-29T09:35:17.084-05:00Machine Learning and Complexity<p> </p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjB-e4HIPenlJclDSenALB6otAw1Nga8deJ3zx3JoMuf41bWFlfy6u4fi-agHPIClWKvkOGcuQRyXbfXXI__l8YpgFjXBY17Y05mdXCMT6bZUbgoILvkQ7D2t4JRNvqFuG-LNaQMRC0HphwBVu3DoVnnHj1ojqbfCXov8yZaRNlj9hoGpqBAQ/s1024/DALL%C2%B7E%202022-09-17%2014.00.36%20-%20Schloss%20Dagstuhl%20in%20the%20style%20of%20monet.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1024" data-original-width="1024" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjB-e4HIPenlJclDSenALB6otAw1Nga8deJ3zx3JoMuf41bWFlfy6u4fi-agHPIClWKvkOGcuQRyXbfXXI__l8YpgFjXBY17Y05mdXCMT6bZUbgoILvkQ7D2t4JRNvqFuG-LNaQMRC0HphwBVu3DoVnnHj1ojqbfCXov8yZaRNlj9hoGpqBAQ/w400-h400/DALL%C2%B7E%202022-09-17%2014.00.36%20-%20Schloss%20Dagstuhl%20in%20the%20style%20of%20monet.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Schloss Dagstuhl by Monet by Dall-E</td></tr></tbody></table><br /><p></p><p>At Dagstuhl <a href="https://blog.computationalcomplexity.org/2022/09/thirty-years-of-dagstuhl.html">earlier this month</a>, I hung out for a little bit with the participants of the other seminar, <a href="https://www.dagstuhl.de/en/program/calendar/semhp/?semnr=22372">Knowledge Graphs and their Role in the Knowledge Engineering of the 21st Century</a>. Knowledge graphs are what you would expect them to be, nodes are objects like "Berlin" and "Germany" with directed edges with labels like "capital". Think of having knowledge graphs of hundreds of millions of nodes and how that could help answer queries about the world. These secondary workshops are shorter and focus on creating a new vision, in this case how to maximize the importance of knowledge graphs in an increasing ML-focused world.</p><p>Perhaps we need such a visioning seminar for complexity. While we often get lost in the mathematical questions and techniques in our field, computational complexity is designed to understand the difficulty of solving various problems. Machine learning and advances in optimization should be changing that conversation. If you imagine a world where P = NP (and I did exactly that in chapter 2 of <a href="https://goldenticket.fortnow.com/">my 2013 book</a>) much of what you consider is <a href="https://blog.computationalcomplexity.org/2020/12/optiland.html">starting to happen anyway</a>. ML does fail to break cryptography but then again, isn't this the best of all possible worlds? </p><p>Look at what Scott Aaronson <a href="https://scottaaronson.blog/?p=122#:~:text=If%20P%3DNP%2C%20then%20the,strategy%20would%20be%20Warren%20Buffett.">said back in 2006</a>.</p><blockquote>If P=NP, then the world would be a profoundly different place than we usually assume it to be. There would be no special value in “creative leaps,” no fundamental gap between solving a problem and recognizing the solution once it’s found. Everyone who could appreciate a symphony would be Mozart; everyone who could follow a step-by-step argument would be Gauss; everyone who could recognize a good investment strategy would be Warren Buffett. </blockquote><p>If I can be a Monet, can Mozart be far behind? ML trading by some hedge funds are beating Warren Buffett but remember if everyone trades perfectly, no one beats the average. Gauss is going to be trickier but <a href="https://www.quantamagazine.org/in-new-math-proofs-artificial-intelligence-plays-to-win-20220307/">it's coming</a>. There's a reason Scott is <a href="https://scottaaronson.blog/?p=6484">spending a year at OpenAI</a> to understand "what, if anything, can computational complexity contribute to a principled understanding of how to get an AI to do what we want and not do what we don’t want".</p><p></p>https://blog.computationalcomplexity.org/2022/09/machine-learning-and-complexity.htmlnoreply@blogger.com (Lance Fortnow)5tag:blogger.com,1999:blog-3722233.post-1313340574525713217Tue, 27 Sep 2022 02:02:00 +00002022-09-28T10:37:51.861-05:00Is the complexity of approximating Vertex Cover of degree 3 open? (ADDED LATER-NO)<p> RECALL:</p><p>A max-problem f has a A P Time App Scheme (PTAS) if there is an algorithm ALG such that</p><p> ALG(\epsilon) \ge (1-\epsilon)f(x).</p><p><br /></p><p>A min-problem f has a A P Time App Scheme (PTAS) if there is an algorithm ALG such that</p><p> ALG(\epsilon) \le (1+\epsilon)f(x).</p><p><br /></p><p>(Note that the poly can depend on epsilon so it may be something like n^{1/epsilon}.)</p><p><br /></p><p>MAX3SAT is, given a formula with \le 3 literals per clause, find an assignment</p><p>that maximized the number of clauses satisfied.</p><p><br /></p><p>VCB-a is Vertex cover where graphs have degree \le a</p><p><br /></p><p>The following are known:</p><p>0) MAX3SAT is in APX.</p><p>1) The PCP paper, <a href="https://doi.org/10.1145/278298.278306">here</a>, showed that if MAX3SAT has a PTAS then P=NP.</p><p>2) Papadimitriou and Yannakakis (<a href="https://doi.org/10.1016/0022-0000(91)90023-X">here</a>) had showed much earlier that MAX3SAT \le VCB-4 with an approx preserving reduction.</p><p>3) From (1) and (2) we have that VCB-4 has a PTAS then P=NP. (VC is in APX by an easy 2-approx).</p><p>4) Clearly VCB-2 is in P.</p><p>The following seems to be open, though if you know otherwise pleae leave a comment:</p><p><br /></p><p>Is VCB-3 a) in P? b) NPC? (ADDED LATER- NPC- See comments.) </p><p>Is the following true: if VCB-3 has a PTAS then P=NP. (ADDED LATER- NO PTAS-See Comments)</p><p><br /></p><p>NOTE- all of the above is true for Ind Set-4 and Dom Set-4. So that leads to more open problems.</p><div><br /></div>https://blog.computationalcomplexity.org/2022/09/is-complexity-of-vertex-cover-of-degree.htmlnoreply@blogger.com (gasarch)6tag:blogger.com,1999:blog-3722233.post-6673399999358490980Wed, 21 Sep 2022 20:48:00 +00002022-09-21T15:51:00.831-05:00POSTED UPDATED VERSION OF Computers and Intractability: A guide to Algorithmic Lower Bounds posted (New title) <p>We have posted a revised version of </p><p><br /></p><p><i>Computational Intractability: A Guide to Algorithmic Lower Bounds</i></p><p>by Demaine-Gasarch-Hajiaghayi</p><p>The book is <a href="https://hardness.mit.edu/">here</a>.</p><p>(For the original post about it, edited it to use the new title (see below), see <a href="https://blog.computationalcomplexity.org/2022/08/computers-and-intractability-guide-to.html">HERE</a>.) </p><p><br /></p><p>We <i>changed the title</i> (the title above is the new one) </p><p>since the earlier title looked <i>too much</i></p><p>like the title of Garey's and Johnson's classic. While that was intentional we </p><p>later felt that it was <i>too close</i> to their title and might cause confusion. </p><p>Of course changing the title might <i>also</i> cause confusion; however, </p><p>this post (and we will email various people as well) will stem that confusion. </p><p><br /></p><p>We welcome corrections, suggestions and comments on the book. Email us at <a href="mailto:hardness-book@mit.edu">hardness-book@mit.edu</a></p><p><br /></p>https://blog.computationalcomplexity.org/2022/09/posted-updated-version-of-computers-and.htmlnoreply@blogger.com (gasarch)3tag:blogger.com,1999:blog-3722233.post-6364865158369002106Mon, 19 Sep 2022 19:02:00 +00002022-09-19T14:02:02.362-05:00There are two different definitions of Integer Programming. Why? <p>Alice and Bob have the following conversation.</p><p>===============================</p><p>ALICE: In your book you define INT PROG as, given a matrix A and vectors b,c,</p><p>find the integer vector x such that Ax\le b and c DOT x is maximized.</p><p>This is not correct! You also need x\ge 0.</p><p><br /></p><p>BOB: Really? I always heard it without that extra constraint, though I am</p><p>sure they are equivalent and both NP-complete (Alice nods).</p><p>Where did you see it defined with that extra constraint?</p><p><br /></p><p>ALICE:</p><p><a href="https://en.wikipedia.org/wiki/Integer_programming">Wikipedia entry in IP</a><br /></p><p><a href="https://web.mit.edu/15.053/www/AMP-Chapter-09.pdf">Chapter of a book at an MIT website</a><br /></p><p><a href="https://www.sciencedirect.com/topics/mathematics/integer-programming-problem">Something on Science Direct</a><br /></p><p><a href="https://courses.cs.duke.edu/fall12/compsci590.1/introduction.pdf">A course at Duke</a><br /></p><p><a href="https://lara.epfl.ch/w/_media/papadimitriou81complexityintegerprogramming.pdf">An article by Papadimitriou</a> <br /></p><p><a href="https://arxiv.org/pdf/2012.00079.pdf">An article on arxiv</a><br /></p><p>The book <i>Graphs, Networks and Algorithms</i> by Dieter Jungnickel</p><p>Bob, do you have examples where they do not use that extra constraint. </p><p>BOB: </p><p><a href="https://www.mathworks.com/discovery/integer-programming.html">Math Works</a><br /></p><p><a href="https://faculty.math.illinois.edu/~mlavrov/docs/482-fall-2019/lecture33.pdf">Lecture notes from UIUC</a><br /></p><p><a href="https://coral.ise.lehigh.edu/~ted/files/ie418/lectures/Lecture1.pdf">Lecture notes from Lehigh Univ.</a><br /></p><p>The book <i>Parameterized Complexity Theory</i> by Flum and Grohe</p><p>The book <i>Computers and Intractability : A Guide to the Theory of NP-Completeness</i> by Garey and Johnson</p><p>ALICE: Both of our lists are impressive. So now what? </p><p>--------------------------------------------------------------------</p><p>(This is Bill again.)</p><p>What indeed!</p><p>1) Why are there two definitions of Int Prog?</p><p>2) When is it good to use which one? </p><p><br /></p><p><br /></p>https://blog.computationalcomplexity.org/2022/09/there-are-two-different-definitions-of.htmlnoreply@blogger.com (gasarch)5tag:blogger.com,1999:blog-3722233.post-6674583717006469349Thu, 15 Sep 2022 20:41:00 +00002022-09-19T11:00:38.293-05:00Monarachy: A Problem with Definitions<p> As I am sure you know, Queen Elizabeth II passed away at the age of 96 recently. I am not a royal-watcher, but I am a royal-watcher-watcher. That is, the question of why people care about the lives of these people intrigues me. A few notes</p><p>1) Was she a <i>good Queen?</i> People tend to think so; however, since the job is somewhat ill-defined its hard to say. </p><p>2) The Queen is supposed to be above politics (she does not vote- I was surprised to find out that legally she can, but she really can't). We know very few of Queen Elizabeth II's opinions on political events. But the notion of <i>political </i>is not well defined. One would think that if she did an appeal for people to take the COVID vax that would not be political, but somehow it is (I do not know if she did such an appeal). King Charles III believes in global warming and that we need to do something about it. This again should not be political but is. </p><p>3) She is the second longest reigning Monarch. First is King Louis XIV who first became king at the age of 4. I had a blog complaining about this <a href="https://blog.computationalcomplexity.org/2022/05/queen-elizabeth-is-3rd-longest-reigning.html">here</a>. However, there is a more interesting point I want to make. From the first to the last day of King Louis XIV reign not much had changed. Technology, politics, other things just didn't change much. By contrast the world changed A LOT between Queen Elizabeth II first and last day:</p><p>a) The British were an important power in 1952. Less so now.</p><p>b) When her father died she was in Kenya and it took 4 hours to get the news to her. Now that would be immediate. </p><p>c) Divorce was considered bad in 1952 and is why King Edmond VIII could not be king (he wanted to marry a twice-divorced woman whose ex-husbands were still alive). And now three of the Queen's children have been divorced.</p><p>d) Gay people.. enough said. There has even been a royal gay wedding, see <a href="https://www.dailymail.co.uk/news/article-5849971/Royal-familys-gay-wedding-story-Queens-cousin-Lord-Ivar-Mountbatten.html">here</a></p><p>Black people (can't call them African-Americans), Women,... you fill it in. </p><p>e) When Charles wanted to get married it seemed to be important that he marry a virgin. We cannot imagine this mentality anymore. When Prince William and Kate got married they were already living together and this was NOT an issue for ANYONE. I looked up what the Church of England thought of it and all I got was some very bland comments like <i>That's what young people do nowadays. </i></p><p>3) Is the monarchy a good thing? As an American I feel I do not have a right to an opinion. If the citizens of the United Kingdom approve of the monarch (polls show they do) then who am I do tell them they are wrong? Even so, lets look at reasons for it</p><p>a) Tourism. It has been said that the Monarchy leads to MONEY from tourism. So it is worth the price? Nobody seems to know and it would be hard to tell. However, I don't think the citizens of the United Kingdom view money as the reason for Monarchy. The American analog is giving Disneyland tax breaks to be in Florida which generates jobs. I doubt they think of the Monarchy in those mundane transactional terms. </p><p>b) CS Lewis said </p><p><i>Where men are forbidden to honour a king they honour millionaires, athletes, or film stars instead: even famous prostitutes and gangsters. For spiritual nature, like bodily nature, will be served; deny it food and it will gobble poison.</i></p><p>This is bit odd- they must all pretend to like the monarchy to make it work. A long time ago when Charles and Dianna were both having affairs, 80% of the citizens the United Kingdom thought that was okay so long as they are discreet so <i>the people</i> don't find out. But- those ARE the people.</p><p>Also odd- CS Lewis was a theologian and a believing Christian; however, his comment above can apply to God as well as to Kings. </p><p><i><br /></i></p><p><br /></p><p><br /></p><p><br /></p>https://blog.computationalcomplexity.org/2022/09/monarachy-problem-with-definitions.htmlnoreply@blogger.com (gasarch)5tag:blogger.com,1999:blog-3722233.post-4092582253443093216Mon, 12 Sep 2022 15:26:00 +00002022-09-12T10:26:51.998-05:00Thirty Years of Dagstuhl<p> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiAVV6vqRxQ0GiKOwjxUJJsrSy10_N1Rnaq7CSWN1LgmRkcVyYHAp5sLgwslboCRbhHq3s6iMU9bSHGJlLBUthZUpI750kpeBrLOkMQcLtDBumFlxNfU-mSDwmO_8nRgw9onQW6AVeluj2ZL1-oGuWqCRxbIVJyT5OZAsdPSTc-BM8UqwioQ/s2668/PXL_20220912_120021005.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="2259" data-original-width="2668" height="339" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiAVV6vqRxQ0GiKOwjxUJJsrSy10_N1Rnaq7CSWN1LgmRkcVyYHAp5sLgwslboCRbhHq3s6iMU9bSHGJlLBUthZUpI750kpeBrLOkMQcLtDBumFlxNfU-mSDwmO_8nRgw9onQW6AVeluj2ZL1-oGuWqCRxbIVJyT5OZAsdPSTc-BM8UqwioQ/w400-h339/PXL_20220912_120021005.jpg" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Dagstuhl old-timers at the original castle<br /></td></tr></tbody></table><br /></p><p>I'm back at Dagstuhl for the seminar on <a href="https://www.dagstuhl.de/en/program/calendar/semhp/?semnr=22371">Algebraic and Analytic Methods in Computational Complexity</a>. My <a href="https://www.dagstuhl.de/en/program/calendar/semhp/?semnr=9206">first seminar</a> at Dagstuhl was back in 1992. I've been coming for thirty years and have been here roughly thirty times. My <a href="https://blog.computationalcomplexity.org/2019/03/back-at-dagstuhl.html">last trip</a> was pre-covid (virtual Dagstuhls don't count) and I really needed this chance to hang out and talk complexity with colleagues old and new.</p><p>Some changes since my last trip. The room doors have locks (there are rumors of an incident). You have to create your own keycard on a new machine logging into your Dagstuhl account. I had a long random password through a password manager and it was not so easy as process.</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLRrLcyKcZLTsqhWGocXuS13xG4yxOJNC9A0xL4mwzmXB8KXWwVTEsW4jF5lST7LAfHNbb_z4nwmOQarS1dwdoSwQYg7IX6NdpNqGkriuzDM4M1mP3rgiR99bV2XOAVr2iJvPsyGHBG6ECrwqYuR65Ok9uXvS_CvxogulpL0Eph-4xPLW9EA/s4080/PXL_20220912_122728903.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3072" data-original-width="4080" height="241" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLRrLcyKcZLTsqhWGocXuS13xG4yxOJNC9A0xL4mwzmXB8KXWwVTEsW4jF5lST7LAfHNbb_z4nwmOQarS1dwdoSwQYg7IX6NdpNqGkriuzDM4M1mP3rgiR99bV2XOAVr2iJvPsyGHBG6ECrwqYuR65Ok9uXvS_CvxogulpL0Eph-4xPLW9EA/s320/PXL_20220912_122728903.jpg" width="320" /></a></div><p>The main conference room has been updated with tech for hybrid meetings, and new led lights. Books were removed from the library to create a coffee breakout space.</p><p>No Bill this time so no <a href="https://blog.computationalcomplexity.org/search?q=typecast">typecasts</a>. Still the best part of the week is talking and hearing about complexity. Today I learned about the <a href="https://en.wikipedia.org/wiki/Sperner%27s_lemma#Oriented_variants">orientations of Sperner's lemma</a>, that there is one more triangle oriented according to the direction of the corner vertices than those oriented the other way. Christian Ikenmeyer used this fact to motivate a study of closure properties of #P-functions.</p>https://blog.computationalcomplexity.org/2022/09/thirty-years-of-dagstuhl.htmlnoreply@blogger.com (Lance Fortnow)1tag:blogger.com,1999:blog-3722233.post-1874664086811883884Wed, 31 Aug 2022 19:35:00 +00002022-08-31T14:41:34.039-05:00The NIST Process for Post-Quantum Cryptography<div><i>Guest post by <a href="https://www.cs.umd.edu/~jkatz/">Jonathan Katz</a></i></div><div><br /></div>Over the past few months there have been several interesting developments in the <a href="https://csrc.nist.gov/Projects/post-quantum-cryptography">NIST post-quantum standardization process</a>.<div><br /></div><div>By way of background, since the advent of <a href="https://en.wikipedia.org/wiki/Shor%27s_algorithm">Shor's algorithm</a> in 1994 we have known that a large-scale, general-purpose quantum computer would be able to break all currently deployed public-key cryptography in (quantum) polynomial time. While estimates vary as to when (or even whether!) quantum computers will become a realistic threat to existing public-key cryptosystems, it seems prudent to already begin developing/deploying newer "post-quantum" schemes that are plausibly secure against quantum computers.</div><div><br /></div><div>With the above in mind, NIST initiated an open process in 2017 for designing post-quantum cryptographic standards. Researchers from around the world submitted candidate algorithms for public-key encryption/key exchange and digital signatures. These were winnowed down over a series of rounds as cryptographers publicly debated the relative merits of different proposals, or showed security weaknesses in some candidates.</div><div><br /></div><div>On July 5 of this year, NIST <a href="https://nvlpubs.nist.gov/nistpubs/ir/2022/NIST.IR.8413.pdf">announced</a> that it had selected four of the submissions as finalists for standardization. Only one candidate for public-key encryption was chosen, along with three digital signature schemes. Three of the four selected algorithms rely on the hardness of lattice problems; the only non-lattice scheme is a hash-based signature scheme. (It is possible to build digital signatures using "symmetric-key" assumptions alone.) In addition, four other public-key encryption schemes not based on lattices were designated for further study and possible standardization at a later point in time.</div><div><br /></div><div>Less than one month later, <a href="https://eprint.iacr.org/2022/975">Castryck and Decru announced</a> a <strong>classical</strong> attack on SIKE, one of the public-key encryption schemes chosen for further study. <a href="https://sike.org/">SIKE</a> is based on a conjectured hard problem related to isogenies on supersingular elliptic curves. The attack was not just theoretical; the researchers were able to implement the attack and run it in less than a day or less, depending on the security level being considered. Details of the attack are quite complex, but Galbraith <a href="https://ellipticnews.wordpress.com/2022/07/31/breaking-supersingular-isogeny-diffie-hellman-sidh/">gives a high-level overview</a>. <a href="https://ellipticnews.wordpress.com/2022/08/12/attacks-on-sidh-sike/">Subsequent improvements</a> to the attack followed.</div><div><br /></div><div>It is worth adding that the above follows an <a href="https://eprint.iacr.org/2022/214">entirely classical attack</a> shown roughly six months earlier on Rainbow, another submission to the NIST standardization process that made it to the 3rd round. (Rainbow is a signature scheme that relies on an entirely different mathematical problem than SIKE.) For completeness, note that none of the four finalists are impacted by any of these attacks.</div><div><br /></div><div>A few reflections on the above:</div><div><ul style="text-align: left;"><li>It is amazing that the factoring and RSA problems are still hard (for classical computers), more than 40 used after they were proposed for cryptography. The same goes for the discrete-logarithm problem (in certain groups).</li><li>It is not easy to find other hard mathematical problems! <a href="https://en.wikipedia.org/wiki/McEliece_cryptosystem">Code-based cryptography</a> has been around about as long as factoring, but has been somewhat unpopular for reasons of efficiency. Lattice-based cryptosystems still seem to give the leading candidates.</li><li>We need more (non-cryptographers) studying cryptographic assumptions. The attacks on SIKE involved deep mathematics; attacks on lattice problems may involve algorithmic ideas that cryptographers haven't thought of.</li></ul></div>https://blog.computationalcomplexity.org/2022/08/the-nist-competition-for-post-quantum.htmlnoreply@blogger.com (Lance Fortnow)1tag:blogger.com,1999:blog-3722233.post-4599175495420459984Thu, 25 Aug 2022 03:09:00 +00002022-09-21T15:48:58.535-05:00Computational Intractability: A Guide to Algorithmic Lower Bounds. First draft available! Comments Welcome!<p>(This post is written by Erik Demaine, William Gasarch, and Mohammad Hajiaghayi)</p><p>In 1979 Garey and Johnson published the classic</p><p> <i>Computers and Intractability: A Guide to NP-Completeness</i></p><p>There has been A LOT of work on lower bounds since then.</p><p>Topics that were unknown in 1979 include</p><p>Parameterized Complexity,</p><p> Lower bounds on approximation,</p><p>Other hardness assumptions (ETH, 3SUM-conjecture, APSP-conjecture, UGC, Others), </p><p>Online Algorithms,</p><p>Streaming Algorithms, </p><p>Polynomial Parity Arguments, </p><p>Parallelism, and </p><p>Many new problems have been shown complete or hard in NP, PSPACE, and other classes.</p><p><br /></p><p>Hence a sequel is needed. While it is impossible for one book to encompass all, or even a large fraction, of the work since then, we are proud to announce a book that covers some of that material:</p><p><i>Computational Intractability: A Guide to Algorithmic Lower Bounds</i></p><p>by Erik Demaine, William Gasarch, and Mohammad Hajiaghayi. MIT Press. 2024</p><p>See <a href="https://hardness.mit.edu/">HERE</a> for a link to a first draft.</p><p>We welcome corrections, suggestions and comments on the book. Either leave a comment on this blog post or emailing us at <a href="mailto:hardness-book@mit.edu">hardness-book@mit.edu</a></p><p><br /></p><p><br /></p>https://blog.computationalcomplexity.org/2022/08/computers-and-intractability-guide-to.htmlnoreply@blogger.com (gasarch)3tag:blogger.com,1999:blog-3722233.post-5383207883567807338Mon, 22 Aug 2022 13:04:00 +00002022-08-22T08:04:18.392-05:0020 Years of the Computational Complexity Weblog<p></p><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6GDCODRrARsTAby27oCbx62tuXwL99PLAQoF3EAnHJ_VYJHxBeQBEW4WDsti4OYckqE0f6i3_pnSOpEoApn4H-Wxdn3XoZzhM5W-xjKtAdVcWE3-61i-McxSL6kosop34uFHoMflbs2O4lHftdkjoW0SCudrJf3pC3YtQY7J1nmhUnc9VBQ/s1024/DALL%C2%B7E%202022-08-22%2008.00.34%20-%20birthday%20cake%20with%20green%20frosting%20and%2020%20candles.png" imageanchor="1"><img alt="Birthday Cake" border="0" data-original-height="1024" data-original-width="1024" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6GDCODRrARsTAby27oCbx62tuXwL99PLAQoF3EAnHJ_VYJHxBeQBEW4WDsti4OYckqE0f6i3_pnSOpEoApn4H-Wxdn3XoZzhM5W-xjKtAdVcWE3-61i-McxSL6kosop34uFHoMflbs2O4lHftdkjoW0SCudrJf3pC3YtQY7J1nmhUnc9VBQ/w200-h200/DALL%C2%B7E%202022-08-22%2008.00.34%20-%20birthday%20cake%20with%20green%20frosting%20and%2020%20candles.png" title="Dall-E baked us a cake" width="200" /></a></div><p>I <a href="https://blog.computationalcomplexity.org/2002/08/this-is-my-complexity-web-log.html">first posted</a> on this blog twenty years ago today, still the oldest and longest running weblog in theoretical computer science, possibly in all of computer science. In those twenty years we've had nearly 3000 posts and over 23,000 comments and 10,000,000 page views. Bill Gasarch <a href="https://blog.computationalcomplexity.org/2007/03/complexity-blog-lives.html">joined me</a> officially as a co-blogger over 15 years ago on March 30, 2007. </p><p></p><p>We've seen <a href="https://blog.computationalcomplexity.org/2014/12/favorite-theorems-recap.html">major results in computational complexity</a> but the biggest challenges remain, in particular major separations of complexity classes. We've also had a front row seat to a computing revolution with the growth of cloud and mobile computing, social networks connecting us for better or for worse, and incredible successes of machine learning. It's almost as though we've been handed an oracle that gives us much of the goodness of P = NP while leaving cryptography intact. </p><p>What will the next twenty years bring? We'll be watching, posting and <a href="https://twitter.com/fortnow">tweeting</a>. Hope you keep reading and commenting. </p>https://blog.computationalcomplexity.org/2022/08/20-years-of-computational-complexity.htmlnoreply@blogger.com (Lance Fortnow)4tag:blogger.com,1999:blog-3722233.post-483004697033875840Thu, 18 Aug 2022 14:47:00 +00002022-08-18T09:47:12.585-05:00Conference Modality<p>We have had an almost normal summer conference season, for some sense of normal. At one of those conferences I participated in an hybrid conversation about whether the conference should be in-person, virtual or hybrid the following year. Here are some general thoughts.</p><p><b>In-Person</b></p><p>The traditional conference format. People travel from near and far to a hotel, conference center or campus location. Talks given in large rooms, often in parallel. A reception, some social activities, participants gathering in small groups to go out for meals. </p><p>Positives: In-person maximizes interaction between participants. Being physically away from your home means you can focus your time on the conference and your fellow participants. This was more true before the mobile devices/laptops/internet days, but still most participants will spend more time on-site than on-line.</p><p>Negatives: Expensive--with registration, hotel and air fare, even a domestic participant could have to pay $2000 or up, higher for those traveling internationally. Visas can be hard to get. Some still feel unsafe in large groups. People often leave early, pity the last speakers. And don't forget the carbon footprint. </p><p>As countries declare war on other countries or states deny certain rights, there is a push against meetings in certain places. Note the disclaimer for next year's <a href="https://fcrc.acm.org/">FCRC</a>. You might upset some people if you have conferences at these locations (and others if you don't).</p><p><b>Virtual</b></p><p>Virtual conferences would never in the past have been taken seriously but Covid forced our hands. </p><p>Talks are streamed or pre-recorded. Some interaction with chats in talks, zoom get togethers or though a systems like <a href="https://www.virtualchair.net/">virtual chair</a>. Even if we had a perfect "metaverse" experience where we could get together as though we were in person, not being there in person means we wouldn't make it a priority.</p><p>The big advantages are costs are low, it's easy to attend talks, and no danger of spreading disease. Still a virtual conference can feel too much like just a collection of streamed and recorded talks.</p><p><b>Hybrid</b></p><p>So let's make the conference hybrid and have the best of both worlds. Alas, it doesn't work out that way. It's nearly impossible to have good interaction between in-person and virtual participants--basically you have to run two separate meetings. Do you allow virtual talks or require an author to show up in person. </p><p>How do you set prices? Lower prices for virtual increases assess but decreases in-person attendance. Participants (or their advisors) might opt to save expenses and attend virtually instead of in-person, reducing the networking opportunities for everyone. </p><p>Most conferences tend to take the hybrid route to avoid the complaints if one went fully in-person or virtual, but hybrid just pretty much guarantees a mediocre experience for all.</p><p><b>Opinion</b></p><p>My suggestion is some years run the conference virtually and others in hybrid. We already have too many conferences, a byproduct of our field using conferences as the primary publication venue. I suggest following conferences like the International Congress of Mathematicians or the Game Theory World Congress, held every four years. If the main conference of a field is held every four years, researchers, particularly senior researchers, make a bigger effort to be there. You can have the virtual meetings the other years so researchers, particularly students, can continue to present their work.</p><p>No easy solutions and CS conferences have <a href="https://cacm.acm.org/magazines/2009/8/34492-viewpoint-time-for-computer-science-to-grow-up/fulltext">not worked well for years</a>. Maybe the struggle to define future conferences will allow us to focus more on the connecting researchers than just "journals that meet in a hotel".</p>https://blog.computationalcomplexity.org/2022/08/conference-modality.htmlnoreply@blogger.com (Lance Fortnow)4