CryptoMiniSat 5.0.1 released — with MIT license

A new version of CryptoMiniSat, 5.0.1 has been released. It is essentially only a release to mark the move to a much more permissive, MIT license. I am changing the license so that everyone can use the system as they wish, however they wish. I want to give back to the community I have been part of for so long, and so I am making this change. Thank you all for using the solver, it makes me happy that I have been able to help some with my hobby work.

Texas Executed Offenders’ Last Words

An artist friend of mine gave me this idea, so here is the list of the most used words of those executed in Texas, from their last statement:

 

Eight Pro Tips on Creating Better Software

I have been writing software for more than 20 years now. I thought it’s about time to gather my experiences and write some advice on building better software.

1. Solve the right problem

It is all too often that one tries solving something  before understanding the problem at hand. We have a certain understanding of what the issue is, write something to solve it, but it turns out that we wrote the wrong solution because we misunderstood the problem. Do some research, read some articles, talk to people and read some books before attempting to solve a problem.
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Memory layout of clauses in MiniSat

I have been trying to debug why some MiniSat-based solvers perform better at unit propagation than CryptoMiniSat. It took me exactly 3 full days to find out and I’d like to share this tidbit of information with everyone, as I think it might be of interest and I hardly believe many understand it.

The mystery of the faster unit propagation was that I tried my best to make my solver behave exactly as MiniSat to debug the issue, but even though it was behaving almost identically, it was still slower. It made no sense and I had to dig deeper. You have to understand that both solvers use their own memory managers. In fact, CryptoMiniSat had a memory manager before MiniSat. Memory managers are used so that the clauses are put close to one another so there is a chance that they are in the same memory page, or even better, close enough for them not to waste memory in the cache. This means that a contiguous memory space is reserved where the clauses are placed.

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