Thursday, October 19, 2017

The Amazon Gold Rush

Unless you have hidden under a rock, you've heard that Amazon wants to build a second headquarters in or near a large North American city. Amazon put out a nice old fashioned RFP.
Please provide an electronic copy and five (5) hard copies of your responses by October 19, 2017 to amazonhq2@amazon.com. Please send hard copies marked “confidential” between the dates of October 16th – 19th to ...
Hard copies? Just like the conference submissions of old. Key considerations for Amazon: A good site, local incentives, highly education labor pool and strong university system, near major highways and airports, cultural community fit and quality of life.

I've seen companies put subsidiaries in other cities, or moved their headquarters away from their manufacturing center, like when Boeing moved to Chicago. But building a second headquarters, "a full equal" to their Seattle campus, seems unprecedented for a company this size. Much like a company has only one CEO or colleges have one President, having two HQs questions where decisions get made. Amazon is not a typical company and maybe location means less these days.

Atlanta makes many short lists. We've got a burgeoning tech community, a growing city, sites with a direct train into the world's busiest airport, good weather, low cost of living and, of course, great universities. Check out the Techlanta and ChooseATL.

So am I using Amazon's announcement as an excuse to show off Atlanta? Maybe. But winning the Amazon HQ2 would be transformative to the city, not only in the jobs it would bring, but in immediately branding Atlanta as a new tech hub. Atlanta will continue to grow whether or not Amazon comes here but high profile wins never hurt.

Many other cities make their own claims on Amazon and I have no good way to judge this horse race (where's the prediction market?). Impossible to tell how Amazon weighs their criteria and it may come to which city offers the best incentives. Reminds me of the Simons Institute Competition announced in 2010 (Berkeley won) though with far larger consequences.

Monday, October 16, 2017

Reductions between formal languages

Let EQ = {w : number of a's = number of b's }

Let EQO = { anbn : n ∈  N} (so its Equal and in Order)

Typically we do the following:

Prove EQO is not regular by the pumping lemma.

Then to show EQ is not regular you say: If EQ was regular than EQ INTERSECT a*b*= EQO is regular, hence EQ is not regular (I know you can also show EQ with the Pumping Lemma but thats not important now.)

One can view this as a reduction:

A  ≤  B

If one can take B, apply a finite sequence of closure operations (e.g., intersect with a regular lang,
complement, replace all a with aba, replace all a with e (empty string), ) and get A.

If A is not regular and A≤ B then B is not regular.

Note that

EQO ≤ EQ ≤ EQ

Since EQO is not regular (by pumping ) we get EQ and \overline{EQ} are not regular.

Hence we could view the theory of showing things not-reg like the theory of NP completeness
with reductions and such. However, I have never seen a chain of more than length 2.

BUT- consider the following! Instead of using Pumping Lemma we use Comm. Comp. I have
been able to show (and this was well known) that

EQ is not regular by using Comm. Comp:

EQH = { (x,y) : |x|=|y| and number of a's in xy = number of b's in xy }

Comm Complexity of EQH is known to be log n  + \Theta(1). Important- NOT O(1).

If EQ is regular then Alice and Bob have an O(1) protocol: Alice runs x through the DFA and
transmits to Bob the state, then Bob runs y from that state to the end and transmits 1 if ended up in an accept state, 0 if not.

But I was not able to show EQO is not regular using Comm Complexity. SO imagine a bizzaro world where I taught my students the Comm Comp approach but not the Pumping Lemma. Could they prove that EQO is not regular. For one thing, could they prove

EQO ≤ EQ  ?

Or show that this CANNOT be done.

Anyone know?

One could also study the structure of the degrees induced by the equiv classes.
If this has already been done, let me know in the comments.

Thursday, October 12, 2017

Lessons from the Nobel Prizes

We've had a big week of awards with the Nobel Prizes and the MacArthur "Genius" Fellows. The MacArthur Fellows include two computer scientists, Regina Barzilay and Stefan Savage, and a statistician Emmanuel Candès but no theoretical computer scientists this year.

No computer scientists among the Nobel Laureates either but technology played a large role in the chemistry and physics prize. The chemistry prize went for a fancy microscope that could determine biomolecular structure. The LIGO project that measures extremely weak gravitational waves received the physics prize.

In a sign of the times, Jeffrey Hall, one of the medical prize recipients, left science due to lack of funding.

The economics prize went to Richard Thaler who described how people act irrationally but often in predictable ways such as the endowment effect that states the people give more value to an object they own versus one they don't currently have. The book Thinking Fast and Slow by 2002 Laureate Daniel Kahneman does a great job describing these behaviors.

While at Northwestern I regularly attended the micro-economics seminars many of which tried to give models that described the seemingly irrational behaviors that researchers like Thaler brought to light. My personal theory: Humans evolved to have these behaviors because while they might not be the best individual choices they make society better overall.

Monday, October 09, 2017

Michael Cohen

When I first saw posts about Michael Cohen (see here, here, here) I wondered

is that the same Michael Cohen who I knew as a HS student?

It is.  I share one memory.

Michael Cohen's father is Tom Cohen, a physics professor at UMCP.  They were going to a Blair High School Science fair and I got a ride to it (I had some students presenting at it.) In the car with Tom and Michael, Michael began telling is dad that his dad's proofs were not rigorous enough. I was touched by the notion that father and son could even have such a conversation.

Were Tom's proofs rigorous? I suspect that for Physics they were. But the fact that Michael could, as a high school student, read his dad's paper and have an opinion on it, very impressive. And very nice.

Michael was brilliant. It's a terrible loss.

Thursday, October 05, 2017

Is the Textbook Market doomed?

STORY ONE:
I always tell my class that its OKAY if they don't have the latest edition of the textbook, and if they can find it a  cheap, an earlier edition (often on Amazon, sometimes on e-bay), that's fine.  A while back at the beginning of a semester I was curious if the book really did have many cheap editions so I typed in the books name.

I found a free pdf copy as the fourth hit.

This was NOT on some corner of the dark web. This was easy to find and free. There were a few things not quite right about it, but it was clearly fine to use for the class. I wanted to post this information on the class website but my co-teacher was worried we might get in trouble for it, and he pointed out that the students almost surely already know, so we didn't. (I am sure thats correct. When I've discussed this issue with people, they are surprised I didn't already know that textbooks are commonly on the web, easy to find.)

STORY TWO:
I know someone who is thinking of writing a cheap text for a CS course. It will only be $40.00. That is much cheaper than the cost of a current edition of whats out there, and competitive with the used editions, but of course much more expensive than free. I think once students start getting used to free textbooks, even$40.00 is a lot.

STORY THREE (What I do): For discrete math we had slides on line, videos of the lectures on line, and some notes on line. For smaller classes I have my own notes on line. The more I teach a course the better then notes get as I correct them, polish them, etc, every time I teach.  Even so, the notes are very good if you've gone to class but not very good if you haven't (that is not intentional- is more a matter of, say, my notes not having actual pictures of DFA's and NFA's).  I have NO desire to polish the notes more and make a book out of them.  Why do some people have that urge? I can think of two reason though I am sure there are more: (1) To make money. If you get a text out early in a field then this could work (I suspect CLR algorithms text made money). I wonder if Calc I books still make money given how many there are. But in any case, this motivation is now gone--- which is one of the points of this post.  (2) You feel that your way to present (say) discrete math is SO good that others should use it also!  But now you can just post a book or notes on the web, do a presentation at SIGCSE or other comp-ed venues. You don't need to write a textbook. (Personally I think this is a bit odd anyway--- people should have their own vision for a course. Borrowing someone else's seems strange to me.)

DEATH SPIRAL: Books cost a lot, so students buy them cheap or get free downloads, so the companies does not make money so they raise the price of the book, so students buy them cheap...(I"m not going to get into whose fault this is or who started it, I'm just saying that this is where we are now.)

With books either cheap-used or free, how will the textbook market survive? Or will it? Asking around I got the following answers

1) There will always be freshman who don't know that books can be cheap or free. This might help with Calc I and other first-year courses, but not beyond that.

2) There will always be teachers who insist the students buy the latest edition so that they can assign problems easier, e.g., HW is page 103, problems 1,3,8  and page 105 problems 19 and 20. This will help the textbook publishers in that window between the new edition coming out and the book being scanned in. Is that a long window?

3) Some textbooks now come with added gizmos- codes on the web to get some stuff. For the teachers there may be online quizzes. Unfortunately this makes the books cost even more. I personally never found such things useful, but others might.

4) If a student has a scholarship that pays for books, and the students buys the books used on amazon, can the scholarship still pay for them? I ask non-rhetorically. Even if the answer is no, so the student has to buy books at (say) the campus book store (will they still sell books in 10 years?) this is not enough to save the market.

5) Rent-a-books. I've seen these services. But they still cost too much.

6) e-books. If e-books catch on  then that might get rid of the used-book market. And if they are cheap enough that might help. But the flip side- once e-books are out there  it might be even easier to find a free copy online someplace. (Side note- Many people tell me that math books just don't work as e-books.... yet.)

7) The basic problem is cost. Is there a way for publishers to keep costs down? Or is even that too late as students get used to free or free-ish books?

So I ask again, non-rhetorically- is the textbook market doomed?

Sunday, October 01, 2017

Monty Hall (1921-2017) and His Problem

Monty Hall passed away yesterday, best known for co-creating and hosting the game show Let's Make a Deal, a show I occasionally watched as a kid. To the best of my knowledge he's never proven a theorem so why does he deserve mention in this blog?

For that we turn back the clock to 1990 when I was a young assistant professor at Chicago, more than a decade before this blog started, even before the world-wide web. The Chicago Tribune was a pretty good newspaper in those days before Craigslist. Nevertheless, the Sunday Tribune, as well as many other papers across the country, included Parade, a pretty fluffy magazine. Parade had (and still has) a column "Ask Marilyn" written by Marilyn vos Savant, who does not hide the fact that she had the world's highest IQ according the record books in the 1980's.

In 1990, vos Savant answered the following question in her column. Think about the answer if you haven't seen it before.
Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice?
This is the kind of deal Monty Hall might have made on his show and so his name got attached to the problem in a 1976 paper in the American Statistician. Marilyn vos Savant claimed it was an advantage to switch. Many mathematicians at the time wrote into Parade arguing this was wrong--either way you have a 50% chance of winning. Even several of my fellow colleagues initially believed it made no difference to switch. Who was this low-brow magazine columnist to say otherwise? In fact, Marilyn was right.

Here is my simple explanation: If you make the commitment to switch, you will win if you pick a goat in the first round, a 2/3 chance of happening. Thinking it makes no difference is a fallacy in conditional probability, not unlike Mossel's Dice Paradox.

Monty Hall himself ran an experiment in his home in 1991 to verify that Marilyn was correct, though modulo the assumption that the host would always offer to make the switch and that everything was chosen uniformly.

Thanks to Bill Gasarch and Evan Golub for some useful details and links. Bill says "history being history, Monty Hall will be remembered as a great mathematician working in Probability." Maybe not, but it does get him remembered in the computational complexity blog.

Thursday, September 28, 2017

Tragic Losses

I'd like to remember two young people who's lives were taken way too early. I didn't know either well but both played large roles in two different communities.

 Michael Cohen
Michael Cohen, a young researcher in theoretical computer science, passed away. He's had a number of great algorithmic results most notably his solely authored paper giving a polynomial-time algorithm to construct Ramanujan graphs. Luca Trevisan and MSR give their remembrances. Update (10/5): See also Scott Aaronson, which include comments form Michael's mother and father and a Daily Cal article.

Scout Schultz, in a story that made national news, studied computer engineering at Georgia Tech. On Saturday September 16th Scout was shot by a member of the Georgia Tech campus police. A vigil was held the following Monday, quite peaceful until a splinter group (mostly not Georgia Tech students) broke off, marched to the Georgia Tech police department and set a police car on fire.

 Scout Schultz
The death and its aftermath have shooken us all up at Georgia Tech. What has impressed me during this times is the strength of the Georgia Tech student body. Instead of focusing on blame, they have come together to remember Scout, a leader of the LGBQT community on campus. Being in a liberal city in a conservative state, the politics of the student body is quite mixed, but it doesn't divide the students, rather it brings them together. There's hope yet.

Sunday, September 24, 2017

Science fiction viewers used to embrace diversity (or did they) and now they don't (or do they)

(This post is inspired by the choice of a female to be the next Doctor on the TV show Dr. Who. Note that you can't say the next Dr. Who will be female' since Dr. Who is not the name of the character. The name has not been revealed. Trivia: The first Dr. Who episode was the same day Kennedy was shot.)

I give a contrast and then say why it might not be valid:

Star Trek- The Original Series. 1966. There is a black female communications officer, a Russian officer and an Asian officer. And Science Fiction Viewers EMBRACED and APPROVED of this (for the time) diversity.

Modern Time: A black Storm Trooper in Star Wars VII (see here), a black Jimmy Olsen  in Supergirl (see here), female Ghostbusters (see here), a female Doctor on Dr. Who (see here and here) , and even the diversity of ST-Discovery (see here) have upset science fiction viewers.

So what happened in 50 year?

Now I say why this contrast might not be valid.  All items here are speculative, I welcome comments that disagree intelligently. Or agree intelligently. Or raise points about the issue.

1) Science Fiction fans aren't racists and anti-women, they just don't like change. Star Trek: The Original Series didn't have an original cannon to violate. Having a black Captain (ST:DSN) or a female captain (ST:VOY) was a matter of NEW characters and I don't recall any objections. (Were there objections?) If in  the ST reboot they made Captain Kirk black, I suspect there would be objections which the objectors would claim are not racist. Would they be?

2) While the fans that are upset get lots of coverage, they might be the minority. I sometimes see more stuff on the web arguing against the racism then the racism itself.  (A friend of mine in South Carolina told me that whenever a Confederate monument is about to be taken down the SAME 12 people show up to protest but get lots of coverage).

3) Science Fiction has gotten much more mainstream, so the notion that science fiction viewers now do BLAH' is rather odd since its no longer a small community.

4) In 1966 there was no internet (not even in the Star Trek Universe!!) for fans and/or racists to vent their anger.

5) Some of the objections have valid counterparts: "I don't mind Jimmy Olsen being black, I mind him being so handsome, whereas in the Superman Cannon he is not." (Counter: some of the objections are repulsive:; "I don't mind Jimmy Olsen being black, I mind him being a love interest for Supergirl". Gee why is that?)

5a) Another valid' one `storm troopers were all cloned from ONE white guy so there cannot be a black stormtrooper'.  Racism hiding behind  nitpicking? Actual nitpicking?

6) I give the fans back in 1966 too much credit- it was the showrunners who embraced diversity. The fans-- did they care?

6a) I give the showrunners to much credit. ALL Klingons are war-like, ALL Romulans are arrogant, ALL Vulcans are logical (except during Pon Farr), In the more recent shows like ST-TNG ALL  Ferengi are greedy. So the show accepts that stereotypes can be true.

6b) Women were not portrayed that well in the star trek universe, even in the more recent shows.  See 15 real terrible moments for women on Star Trek

7) Even the 1966 ST  was not as diverse as I make it out to be. I doubt it would pass the Bechdel test

two other points of interest

1) In the 1960's Science Fiction was sometimes  used as a way to talk about current issues since talking about them directly would not have been allowed. We can't really talk about real racism in a TV show so we'll have an alien race where they are all half-black, half-white, but differs on how which side (see here). And now?  Racism, sexism, homophobia can all be talked about freely. Hence other media has moved ahead of Science Fiction for diversity.

2) Also of interest, though not science fiction: The Edward Albee estate blocks a production of Who's afraid of Virginia Woolf that was going to cast a black man as Nick (a supporting character- George is the main male character).  See here.  Why the block? Because that is what Albee (who is now dead) requested. What would he think now? Who knows?