Search found 3874 matches

by michiguel
Tue May 06, 2008 5:31 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Fail soft/Fail hard
Replies: 20
Views: 5942

Re: Fail soft/Fail hard

For instance, you have two possible captures when alpha is 0 (draw). You examine the first one and you are checkmated in two moves. That is the best score so far (-MATE02). The next capture, you evaluate that it is impossible to bring the score close to alpha and you prune it. Then you return the b...
by michiguel
Tue May 06, 2008 2:20 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Fail soft/Fail hard
Replies: 20
Views: 5942

Re: Fail soft/Fail hard

I'm not sure exactly what you are describing as the problem, but fail soft is correct, and should never give incorrect bounds if used properly. Properly is the magic word :-) My point is that the only way to make it properly (or safe) is to search all the sibling moves (does not happen in quies()) ...
by michiguel
Mon May 05, 2008 11:42 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Fail soft/Fail hard
Replies: 20
Views: 5942

Re: Fail soft/Fail hard

I'm not sure exactly what you are describing as the problem, but fail soft is correct, and should never give incorrect bounds if used properly. Properly is the magic word :-) My point is that the only way to make it properly (or safe) is to search all the sibling moves (does not happen in quies()) ...
by michiguel
Mon May 05, 2008 10:19 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Fail soft/Fail hard
Replies: 20
Views: 5942

Fail soft/Fail hard

How many of you are using one or the other? I never paid to much attention to this. When I first started, I chosed fail soft because I thought it was ok and forgot about. I recently found a serious problem with it in quies(). I took me several days of debugging. There was nothing wrong with code, bu...
by michiguel
Mon May 05, 2008 8:42 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Pointer to functions
Replies: 12
Views: 4222

Re: Pointer to functions

They are supposed to be slower. However, in certain situations the alternative is to have a switch or a chain of "if else" that involves lots of branches. When would you choose one approach over the other? I know I have to try, but having an educated guess at the beginning helps a lot. Miguel Unles...
by michiguel
Mon May 05, 2008 8:16 pm
Forum: Computer Chess Club: General Topics
Topic: 2008 World Computer Rapid Chess Championships
Replies: 98
Views: 25120

Re: Rule six

Well, that would in principle run into the same problem at level 2, that by the time all moves have bean searched there, the tree from the search of the PV move might be overwritten. At some depth of course this will be no longer true, as the entire PV tree will fit easily in the hash. But it depen...
by michiguel
Sat May 03, 2008 3:52 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Pointer to functions
Replies: 12
Views: 4222

Pointer to functions

They are supposed to be slower. However, in certain situations the alternative is to have a switch or a chain of "if else" that involves lots of branches. When would you choose one approach over the other?

I know I have to try, but having an educated guess at the beginning helps a lot.

Miguel
by michiguel
Fri May 02, 2008 5:45 am
Forum: Computer Chess Club: General Topics
Topic: Exchange sac
Replies: 14
Views: 3392

Re: Exchange sac

A curious fact about the new Glaurung is that it loves to sacrifice the exchange. I don't know why; I haven't changed the material values or anything else that should affect the program's willingness to part with an exchange. Whatever the reason is, I now see Glaurung make unclear or dubious exchan...
by michiguel
Thu May 01, 2008 9:56 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Strelka Reverse Engineered from Rybka: Details Examined
Replies: 24
Views: 16842

Re: Strelka Reverse Engineered from Rybka: Details Examined

The move generator of strelka generates captures in the following order: 1)Captures by knights 2)Captures by bishops 3)Captures by rooks 4)Captures by Queens 5)Captures by the king 6)promotions 7)promotions that are also captures 8)Captures by pawns. I do not think that this order is the most logic...
by michiguel
Wed Apr 30, 2008 11:28 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Nice Math - Strange Conclusions
Replies: 14
Views: 6304

Re: Nice Math - Strange Conclusions

They reported timings from MatLab? That sounds useless, very few chess engines are written in MatLab... They should have written theirs in C and tested it against the real-world code in various open-source chess engines. Also, I strongly suspect that this "if it isn't published, it doesn't exist" t...