Search found 317 matches

by Karlo Bala
Sun Mar 07, 2021 12:00 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Are Bitboards More Intoxicating Than They Are Good?
Replies: 60
Views: 4748

Re: Are Bitboards More Intoxicating Than They Are Good?

Indeed, bitscan methods can be much faster than loops over all bits. What I don't understand is why you would want to do this with any significant frequency. (I can imagine you would do it in the FEN reader for setting up a new position.) Even the twice faster codes loops over 2 x 64 squares to set...
by Karlo Bala
Sun Feb 14, 2021 8:12 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Thought bitboards was faster :-)
Replies: 38
Views: 4569

Re: Thought bitboards was faster :-)

In the two functions in move.c //fill a square 'sq' whith a piece 'p' of color 'c' void fill_sq(int c, int sq, int p) { //update hash code hash_position ^= hash_table[p][sq]; //update position echiquier[sq] = p; //bitboardS set_bit(bb, sq, ALP); clear_bit(bb, sq, NOP); if(c == BLANC) { set_bit(bb, ...
by Karlo Bala
Sun Feb 14, 2021 3:31 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: TT: key collisions
Replies: 15
Views: 1540

Re: TT: key collisions

I've just finished a couple refactorings in preparation for adding a transposition table to my engine. I'm now modeling castling rights in my game state (vs. using a moved bit), and both the game state and move now fit in native integers respectively. I've read the Mediocre TT Guide that @Nomis men...
by Karlo Bala
Sun Feb 14, 2021 3:17 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Thought bitboards was faster :-)
Replies: 38
Views: 4569

Re: Thought bitboards was faster :-)

Bitboards are not automagically faster, but most often open up some possiblities for further optimizations. For example, your function void set_bit(U64 *pbitboard, int y, int type) { U64 x = pbitboard[type]; x = (BIT[y] | x); pbitboard[type] = x; } could be simplified into pbitboard[type] |= (U64)1...
by Karlo Bala
Sat Feb 06, 2021 4:45 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Strange negamax behaviour
Replies: 12
Views: 2181

Re: Strange negamax behaviour

I have just tried your recommendations, but with no success. I decided to test alphabeta without quiescence search, and it actually began giving more reasonable lines like: 1. Nc3 Nf6 2. e4 e5 3. Nf3 Bb4 4. Ne2 Nxe4 * Although this is far from optimal, I think it is a huge improvement since it real...
by Karlo Bala
Sat Feb 06, 2021 11:45 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Strange negamax behaviour
Replies: 12
Views: 2181

Re: Strange negamax behaviour

I have been struggling with a weird behaviour with my search function for some time now, and I have looked through all the search functions multiple times, but can't seem to see the problem. I am using negamax alpha-beta with principal variation search. There are no pruning methods, reductions or e...
by Karlo Bala
Wed Jan 06, 2021 3:03 pm
Forum: Computer Chess Club: General Topics
Topic: Evaluation of moves from World Championship Games
Replies: 24
Views: 3065

Re: Evaluation of moves from World Championship Games

By today's standards at move 12, we are still in the middle of the opening book. I suspect the results are biased. Try the same but start for example at move 20 to see if there is a difference between the results. In their matches, Kasparov & Karpov played the same opening over and over until beate...
by Karlo Bala
Tue Jan 05, 2021 7:14 pm
Forum: Computer Chess Club: General Topics
Topic: Evaluation of moves from World Championship Games
Replies: 24
Views: 3065

Re: Evaluation of moves from World Championship Games

By today's standards at move 12, we are still in the middle of the opening book. I suspect the results are biased. Try the same but start for example at move 20 to see if there is a difference between the results. In their matches, Kasparov & Karpov played the same opening over and over until beaten...
by Karlo Bala
Wed Dec 30, 2020 9:23 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Are Aspiration Windows Worthless?
Replies: 40
Views: 6427

Re: Are Aspiration Windows Worthless?

It all depends very much upon the quality of the evaluation-function and the quiescence-search. When you play a game against an engine with aproximately the same strength the root-score will deviate only a few centipawns during the whole game and you can set a very narrow window without having to r...
by Karlo Bala
Sat Dec 26, 2020 1:33 am
Forum: Computer Chess Club: General Topics
Topic: Reset-Mobility Chess
Replies: 5
Views: 961

Re: Reset-Mobility Chess

One of the administrators at TCEC, Aloril, has recently developed a variant of chess called Reset-Mobility chess, or R-Mobility chess, which is a generalisation of Lasker chess (where stalemate = 0.75 points) to every chess game that ends in a draw. The goal of Reset-Mobility chess is to force your...