Search found 724 matches

by jwes
Wed Feb 15, 2017 6:08 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Checkers Is Strongly-Solved for 8-pieces
Replies: 98
Views: 30724

Re: Checkers Is Strongly-Solved for 8-pieces

The point was: using WDL only, instead of DTM, can lead to infinite winning attempts (in a won position), or to missing a 50-moves draw (in a lost position that needs more than 50 moves for the opponent to win). Do you realise that using DTM will mess up perfectly fine wins in "chess including the ...
by jwes
Mon Jan 09, 2017 6:34 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: sophesticated Pawn evaluation without hash table ?
Replies: 5
Views: 1531

Re: sophesticated Pawn evaluation without hash table ?

I would strongly suggest implementing a pawn hash table. It makes pawn evaluation almost free (typical hit rates are above 99%).
by jwes
Tue Dec 20, 2016 7:37 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Avoid null move mystery solved
Replies: 0
Views: 507

Avoid null move mystery solved

I have wondered why avoiding null move in very bad positions relative to alpha did not give a noticeable gain. I finally realized the position almost certainly results from a null move by the opponent unless the opponent's last move created the imbalance. This is in accord with earlier test results ...
by jwes
Thu Dec 15, 2016 3:52 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Search-Based Opening Book Construction
Replies: 22
Views: 3491

Re: Search-Based Opening Book Construction

Interesting article. I have a few questions: 1. How do you change the tree into a DAG? a. If you use the naive approach and assume a hash hit is a transposition, a false hit is almost guaranteed to crash your program. b. How do you ensure it is acyclic? 2. If you change your engine, do you have to r...
by jwes
Sat Nov 26, 2016 4:16 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Simple method for simple mates for programs without TBs.
Replies: 8
Views: 2495

Re: Simple method for simple mates for programs without TBs.

It may be better to only use this method when the pawnless position is at the root as your regular evaluation should return a very large score for these positions.
by jwes
Fri Nov 25, 2016 7:51 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Simple method for simple mates for programs without TBs.
Replies: 8
Views: 2495

Re: Simple method for simple mates for programs without TBs.

Kotlov wrote:nothing new... sorry
I hadn't seen it before. Could you quote some sources?
by jwes
Fri Nov 25, 2016 9:28 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Simple method for simple mates for programs without TBs.
Replies: 8
Views: 2495

Simple method for simple mates for programs without TBs.

I found a way to have my program easily perform the basic mates. If there are no pawns on the board, use an evaluation of: material - distance between the two kings as given at chessprogramming.net D=max(|r2−r1|,|f2−f1|) + the piece-square values for the two kings using this table. char ...
by jwes
Sat Nov 19, 2016 12:51 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Order of search techniques
Replies: 10
Views: 1849

Re: Order of search techniques

Then PVS if we're in a PV node. Regular AB call otherwise. I hope you do PVS in the way it is intended: - full window for subtree of first move, - zero window for all other subtrees, researching with full window in case of fail-high If we are using PVS, can we define a PV node as a node where beta>...
by jwes
Thu Oct 27, 2016 11:23 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: A PGN parser
Replies: 31
Views: 6860

Re: A PGN parser

Wouldn't it be sufficient to only generate moves to the given target square, and also only for pieces of the given type? Yes it is possible, the real saving for me is to reduce the number of moves to compare with the given one in san format. With the above optimization I am below 5 seconds now, at ...
by jwes
Tue Oct 25, 2016 1:46 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: A PGN parser
Replies: 31
Views: 6860

Re: A PGN parser

I have seen that although move generation is needed, it can be restricted to only the sensible subset with just a look at the san move, for instance if the PGN move contains 'x' then it is a capture and you can generate just captures. Wouldn't it be sufficient to only generate moves to the given ta...