Monday, November 22, 2010

Workshop on Parallelism, and a "breakthrough" in combinatorial geometry

In the blog world, you're either fast, or dead. I waited a few days to post a note about the upcoming DIMACS workshop on parallelism, and was beaten to the punch by Muthu and Dick Lipton.

At this point, you probably know the major points. Phil Gibbons, Howard Karloff and Sergei Vassilvitskii are organizing a DIMACS workshop on a long-range vision for parallelism, with an emphasis on interaction between practitioners and theoreticians in the area. The workshop looks to be quite interesting, and similar in spirit to the one organized by Uzi Vishkin at STOC 2009 on multicore algorithms.

Utah has a major presence in the world of high performance parallel computing, and we're hiring in this area this year ! From my vantage point, I get a fly-on-the-wall view of developments in the area, and it makes me wonder:
Is the field is now moving too fast for models to even make sense ? 
A case in point: Google's MapReduce infrastructure has taken the world by storm, and you can even run MapReduce "in the cloud" on Amazon's servers. Howard, Sergei and Sid Suri had a very interesting paper on MapReduce at SODA last year, and there's a ton of academic work on algorithm design (in theory and practice) in this model. But if new reports are to be taken seriously, Google itself is moving on from MapReduce to other distributed data management systems.

The most recent "alternative model of computing" that we've encountered is the stream model, and while it had strong links to practice, it's survived this long because of the incredibly interesting theoretical challenges it poses, as well as the rich arsenal of theory concepts that got deployed in the process. I'm curious to see if something similar can happen with these new models of parallelism and multicore computing (over and above PRAM and NC of course)

In other news: readers of Gil Kalai's blog will have heard of the exciting new breakthrough in the realm of combinatorial geometry on the tantalizingly simple problem first posed by Erdos in 1946:
What is the minimum number of distinct distances achievable by a set of n points in the plane ? 
I hope to have a longer guest post up soon on this, so I won't say much right now. What's neat is that this result is the implementation of a larger program/line of attack laid out by Gyorgy Elekes, who sadly died in 2008 before seeing this come to fruition. Micha Sharir has a beautiful writeup with the history of this approach (it predates the new results though). Bill Gasarch has a nice page collecting together the major developments in this area, including links to the Kakeya problem.

p.s Note to other CG bloggers: please do not talk about this problem otherwise Mihai will scold us all ;)

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