> My first (braindead) multi-threaded UCT played weaker with two cores > than one core. How do you combine search trees/results? How do you pick > a move to play?
There were a couple of papers [2] at CG2008 on this subject. The consensus seemed to be that root parallelization [1] was best. In fact Guillaume Chaslot's version got a strength speedup of 3.0 using 2 threads, and 6.5 using 4 threads (dropping to 14.9 with 16 threads). This is of course impossible, and implies the parallel version is somehow doing MCTS better than the single thread algorithm! Darren [1]: Build multiple MCTS trees in parallel, one per thread. No communication. At end add the trees together and use grand total to select move. [2]: http://www.cs.unimaas.nl/g.chaslot/papers/parallelMCTS.pdf and "A Parallel Monte-Carlo Tree Search Algorithm" by Tristan Cazenave (I couldn't seem to find a PDF link.) -- Darren Cook, Software Researcher/Developer http://dcook.org/mlsn/ (English-Japanese-German-Chinese-Arabic open source dictionary/semantic network) http://dcook.org/work/ (About me and my work) http://dcook.org/blogs.html (My blogs and articles) _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
