Author: Ryan B.
Date: 02:19:49 12/12/05
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On December 12, 2005 at 04:58:52, Chrilly Donninger wrote: >I did not follow the CCC-discussion the last months/years. So please do not >"kill" me if I am telling old stuff. I got questions about Rybka from the >Hydra-sponsor so I read yesterday evening some of IM Vasik Rajlichs very >interesting postings in the archive. >Vasik mentions several time MTD(f) and his experience with it. But when playing >with Rybka, it looks like a normal PVS-search. I looked therefore also in the >Rybka-Code. What I have seen so far is typicall PVS-Code. > >From this first look I can say that Rybka is not at all a Fruit clone. > >Chrilly You could look at Fruits source or just read the readme files :) Search algorithm ---------------- The main search algorithm is a classical PVS with iterative deepening. Search enhancements such as a transposition table and null-move pruning are also used (see below). A few details in the PVS implementation are not-so-standard and are there to supposedly enhance the stability of the search (like reducing the consequences of search inconsistencies). For example the re-search window after a scout fail high of score "value" (with value > alpha) is [alpha,beta], not [value,beta]. As another example, I only allow null move when the static evaluation fails high (i.e. eval() >= beta). Whether these features improve the strength of the engine is an open question. Thanks, Ryan
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