The Crafty Team quietly released Crafty 23.6 yesterday.
The source can be downloaded from: Here or here
Changes:
Code: Select all
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* 23.6 Minor tweak to "adaptive hash" code + a fix to the usage warning *
* that failed to explain how many parameters are required. New way *
* of timing the search, replacing the old "easy move" code that was *
* simply too ineffective. Now Crafty computes a "difficulty" level *
* after each iteration. If the best move doesn't change, this *
* level is reduced by 10% of the current value, until it reaches *
* 60% where it stops dropping. If the best move changes during an *
* iteration, it adjusts in one of two ways. If the current *
* difficulty level is less than 100%, it reverts to 100% + the *
* number of different best moves minus 1 times 20%. If the current *
* difficulty level is already >= 100% it is set to 80% of the *
* current value + (again) the number of different best moves - 1 *
* times 20%. Repeated changes can run this up to 180% max. As the *
* search progresses this difficulty level represents the percentage *
* of the nominal target time limit it should use. It still tries *
* to complete the current iteration before quitting, so this limit *
* is a lower bound on the time it will use. Restored an old idea *
* from earlier Crafty versions (and even Cray Blitz), that of *
* trying the killers from two plies earlier in the tree, once the *
* killers for the current ply have been tried. Was a +10 Elo gain, *
* added to about +10 for the new time control logic. Old fail-high *
* restriction removed. At one point in time, a fail-high on the *
* null-window search at the root would cause problems. Crafty was *
* modified so that the fail-high was ignored if the re-search *
* failed low. Removing this produced an 8 Elo gain. *
* *
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My personal testing shows an increase of roughly +52 elo. Enjoy.
Peter