Monday, May 05, 2008

If you find something online download it NOW

A few months ago I was looking into some of the origins of Ramsey Theory (in particular I was looking at what Hilbert needed Hilberts Cube Lemma for) and I came across the following online
Combinatorial Number Theory: Results of Hilbert, Schur, Folkman, and Hindman by Yudi Setyaan. A Thesis submitted in partial fulfillment of the requirements of the defense of Master of Science in the Department of Mathematics and Statistics. Simon Fraser University, July 1998
I printed it out and still have it. It was not helpful for what I wanted, but it was interesting and I'm glad to have it.

Recently I wanted to email it to someone else so I searched for it again. Its gone! Now you have to pay for it at amazon. I also looked for the author on line to see if he might email me a copy (I doubt he gets any money from it and I suspect he would be delighted to find out the someone actually read it.) Couldn't find the authors email address, though I am hopeful that I will.

Moral of the story: If you find a document on line that you may want to keep, DOWNLOAD IT. Do NOT depend on it still being there later.


  1. Actually, wayback machine
    has the interesting feature of keeping copies of PDF and tgz archives.
    It saved me from this situation over and over.

    Nonetheless, I completelgy agree with
    the download&backup policy.

  2. In the extreme case, consider the possibility of keeping a copy of *every* PDF file you ever read. Suppose you are a heavy reader of research papers and you read ten a day. Looking at the PDF files that I have saved, they might average a megabyte each. At this rate it would take under 4 gig per year, which is a trivial amount of storage space (my phone has that much now).

    In other words, I would like to reinforce the case - save EVERYTHING that you might want to read again. The only question is how you will organize it over time. Should we rely upon the commercial digital libraries like ACM, or should we have tools to organize our personal digital libraries? I have my opinion...

  3. Actually, this book is not available for purchase by amazon. What has happened here is that a web site called has simply published the mapping from books to ISBNs on the web, and provided for each book a default link to amazon that will only work if the book is indeed available at amazon.

    And separately, the PDF file seems to have been removed from the web, as happens to many pdf files. But there is probably no connection between the two events.

  4. UPDATE: I found the paper on the web
    in June 2011. I do not know why it left and came back, but I downloaded it this time.