Sunday, October 9, 2011

So...

I really just wanted to write this down somewhere:

1000 instances of n=64 takes up 7.9M.

So 1 million would take up about 7.71G.

And a million is just a tiny ass drop in the bucket.


Notes (or, how do I generate difficult instances of 3-sat?):

According to The State of SAT by Henry Kautz and Bart Selman, a 700 variable problem took a couple months of compute time back in...early 2000s?  Who doesn't date a paper?  This must be a draft.

Two existing (and boring) algorithms for SAT are:

http://en.wikipedia.org/wiki/WalkSAT

http://en.wikipedia.org/wiki/DPLL_algorithm

Problems arising from creating proof trees mentioned in The State of SAT give me hope--modifying my algorithm to produce the proof trees as it runs would be simple if I cared to do it, although the proof trees would not be minimal.

Ok...most of the rest of the paper is boring.  Looks like everyone thinks P != NP.



Oooh, finally, something about hard instance generation:

http://www.is.titech.ac.jp/~watanabe/gensat/

Shit.  Dead links.  Well, at least I know "something about a factorization problem."

Here is Hard Instances for 3-SAT by idk-who in an atrocias ps file intended for slides.  Still more people thinking hard is simply m=n*f

Perhaps what I should really do is measure running time affected by the constant factor X, where m=Xn.  Pretty graphs!  Yay!




Also checked out "Algorithsm for Random 3-SAT" by Abraham D. Flaxman, Microsoft Research.  It pointed me to Where the Really Hard Problems Are.

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