Search found 18563 matches

by hgm
Sat Jul 11, 2020 12:47 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Questions on Razoring and Code Structure for Pruning
Replies: 17
Views: 344

Re: Questions on Razoring and Code Structure for Pruning

The problem is, how do you know you know you attack two pieces? What you propose seems at odds with the principle of 'stand pat'. Which you do (in QS) when the current evaluation is above beta. So you can analyze moves whatever you want at d=1, and decide they are totally winning because you attack ...
by hgm
Sat Jul 11, 2020 12:23 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Questions on Razoring and Code Structure for Pruning
Replies: 17
Views: 344

Re: Questions on Razoring and Code Structure for Pruning

Well, it is very simple. It is not about different margins, it is about that quiet moves can change the static score drastically. e.g: if a pawn push from d2 to d4 attacks a Knight on c5 and that frees a bishop on c1 to attack the opponent queen on g5 ... that's it. To ignore them in the test "outs...
by hgm
Sat Jul 11, 2020 12:00 pm
Forum: Computer Chess Club: General Topics
Topic: Stockfish sewing machine
Replies: 27
Views: 846

Re: Stockfish sewing machine

This is a truly amazing study, which once again teaches us what a beautiful game Chess really is. I admit I couldn't solve it. After hard thinking, just because I was told this is a win, I realized that the crux was to force the black Pawn to move ahead to the unprotected location by zugzwang. But I...
by hgm
Sat Jul 11, 2020 11:20 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Questions on Razoring and Code Structure for Pruning
Replies: 17
Views: 344

Re: Questions on Razoring and Code Structure for Pruning

Outside of the loop, the current state of the art is to consider a position for a test, which evaluation is so bad, that it will most likely not get above alpha, the lower bound. For this purpose, a quiescence search is performed, since the idea is that "only" capture moves can achieve a big differ...
by hgm
Sat Jul 11, 2020 11:01 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Correct way to store and extract mate scores
Replies: 8
Views: 327

Re: Correct way to store and extract mate scores

Well, you could stop iterating when you reach the depth that corresponds to the mate score. If you do a lot of pruning, that still doesn't guarantee you have seen the fastest mate, though. A strongly reduced branch could lead to a quicker mate that it hasn't seen yet. So you can do a few ply extra t...
by hgm
Sat Jul 11, 2020 10:42 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: On-line engine blitz tourney July
Replies: 12
Views: 273

Re: On-line engine blitz tourney July

Oh, I see. The version of mamer you are using doesn't implement McMahon. I never pushed that patch to my source-code repository. :oops:

Anyway, I did that now. So it is available, if you want it.
by hgm
Sat Jul 11, 2020 8:54 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Idea for ID/transposition table
Replies: 4
Views: 122

Re: Idea for ID/transposition table

That holds for any kind of hash cut in a PV node. A more reliable method is to store the PV of TT nodes in the hash table (which, for efficiency reasons, usually means you would use a separate hash table or hash-table extension for PV nodes). Then you will always have the full PV availabe, and you c...
by hgm
Sat Jul 11, 2020 8:36 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: On-line engine blitz tourney July
Replies: 12
Views: 273

Re: On-line engine blitz tourney July

It is usually more efficient to play the McMahon system rather than pure Swiss. Because with such a large strength range of the participants the first 2 or 3 rounds of pure Swiss are wasted on differentiating the field such that you get interesting pairings, rather than guaranteed 1-0 results.
by hgm
Sat Jul 11, 2020 6:25 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Correct way to store and extract mate scores
Replies: 8
Views: 327

Re: Correct way to store and extract mate scores

If I believe the opponent's scores, your mating distances are wrong. At least, I assume that your mate score is 200. When TSCP says -M4, you get 199.87 on the move afterter that. Which would mean mate (or King capture) in 13 ply = 6 moves, while it should have been in 4. This is suspect. What is als...
by hgm
Sat Jul 11, 2020 6:17 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Idea for ID/transposition table
Replies: 4
Views: 122

Re: Idea for ID/transposition table

Most of my engines work that way. It happens sort of automatically, because I don't have a separate RootSearch routine, and it is what I do in every other node. I would have to slip in conditional code only active in the root to suppress it. And it happens quite often; all it needs is that you expec...