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End-game evaluation
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Evert Glebbeek



Joined: 21 Jan 2011
Posts: 866
Location: NL
PostPost subject: Re: End-game evaluation    Posted: Tue Oct 04, 2011 1:02 pm Reply to topic Reply with quote
hgm wrote:
I am getting to the point now to fill Spartacus' material table (which so far only held the B-pair bonus). One of the most important tasks of the material table would be to correct the additive piece-value score for drawish end-games, so that the engine no longer prefers (say) KBK (+325) over KPP (+200).

Interesting. I'd been wondering what the advantage of having a material table would be (not having one, nor much of an idea of what to fill it with), but this is fairly obvious.

Quote:

My question was what end-games need such a correction, and how large that correction should be. Obviously KBK, KNK and KBKB (like B) can be corrected to a hard zero, pruning further search. KNNK is trickier (like KBKN etc., but those don't really need a correction), because there can be checkmates and mate-in-1, and you want the engine to recognize those when it enters KNNK is such a position (e.g. after a forced capture in KNNKQ). So I guess I should evaluate those as zero, but not prune the search (or prune based on the 50-move counter being large enough. I could then apply that same routine to KBKB (unlike), KBKN, KNKN, KRKR (to effect the pruning) if I have it anyway.

I think it's useful to distinguish two situations: not enough material remaining to deliver mate (in which case you can claim a draw and terminate the search immediately) and not enough material to force mate against optimal play. The latter is a lot harder to evaluate and almost certainly should not terminate the search. What I do in that case is discard the material evaluation completely (it's irrelevant) and just return PSQ evaluation for the pieces (maybe even only for the kings), resulting in a small draw-ish score.

I'm afraid that's not much help otherwise though...
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Subject Author Date/Time
End-game evaluation H.G.Muller Tue Oct 04, 2011 11:44 am
      Re: End-game evaluation Evert Glebbeek Tue Oct 04, 2011 1:02 pm
            Re: End-game evaluation H.G.Muller Tue Oct 04, 2011 2:20 pm
      Re: End-game evaluation Oliver Uwira Tue Oct 04, 2011 1:59 pm
      Re: End-game evaluation Jon Dart Tue Oct 04, 2011 2:10 pm
            Re: End-game evaluation Jon Dart Tue Oct 04, 2011 2:13 pm
      Re: End-game evaluation Kevin Hearn Tue Oct 04, 2011 8:19 pm
            Re: End-game evaluation Pawel Koziol Wed Oct 05, 2011 10:46 am
      Re: End-game evaluation H.G.Muller Mon Oct 10, 2011 8:09 am
            Re: End-game evaluation H.G.Muller Mon Oct 10, 2011 9:00 am
                  Re: End-game evaluation Evert Glebbeek Mon Oct 10, 2011 1:04 pm
                  Re: End-game evaluation Ed Schroder Mon Nov 07, 2011 10:15 pm
            Re: End-game evaluation H.G.Muller Wed Oct 19, 2011 10:16 am
                  Re: End-game evaluation Michael Hoffmann Wed Oct 19, 2011 11:48 am
                        Re: End-game evaluation H.G.Muller Wed Oct 19, 2011 1:24 pm
                              Re: End-game evaluation Michael Hoffmann Wed Oct 19, 2011 2:53 pm
                                    Re: End-game evaluation Volker Annuss Wed Oct 19, 2011 4:53 pm
                                    Re: End-game evaluation H.G.Muller Wed Oct 19, 2011 4:54 pm
                                          Re: End-game evaluation H.G.Muller Sat Oct 22, 2011 5:29 pm
                                                Re: End-game evaluation H.G.Muller Mon Nov 07, 2011 7:28 pm
                                                      Re: End-game evaluation Evert Glebbeek Mon Nov 07, 2011 8:33 pm
                                                            Re: End-game evaluation Evert Glebbeek Mon Nov 07, 2011 9:02 pm
                                                                  Re: End-game evaluation H.G.Muller Mon Nov 07, 2011 9:40 pm
                                                            Re: End-game evaluation H.G.Muller Tue Nov 08, 2011 11:16 am
                                                                  Re: End-game evaluation Evert Glebbeek Tue Nov 08, 2011 5:50 pm
                                                                        Re: End-game evaluation H.G.Muller Tue Nov 08, 2011 8:16 pm
                                                                              Re: End-game evaluation Evert Glebbeek Tue Nov 08, 2011 8:52 pm
                                                                                    Re: End-game evaluation H.G.Muller Tue Nov 08, 2011 10:14 pm
                                                      Re: End-game evaluation Karlo Bala Jr. Mon Nov 07, 2011 11:59 pm
                                                            Re: End-game evaluation H.G.Muller Tue Nov 08, 2011 7:30 am
                                                                  Re: End-game evaluation Kevin Hearn Tue Nov 08, 2011 9:58 am
                                                                        Re: End-game evaluation H.G.Muller Tue Nov 08, 2011 12:40 pm
                                                                              Re: End-game evaluation Evert Glebbeek Tue Nov 08, 2011 5:53 pm
      Re: End-game evaluation Mark Lefler Mon Oct 10, 2011 4:08 pm
            Re: End-game evaluation H.G.Muller Mon Oct 10, 2011 9:09 pm
                  Re: End-game evaluation H.G.Muller Mon Oct 10, 2011 9:58 pm
                  Re: End-game evaluation H.G.Muller Tue Oct 11, 2011 8:50 am
                        Re: End-game evaluation H.G.Muller Tue Oct 18, 2011 6:36 pm
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