Search found 18756 matches

by hgm
Sat Oct 31, 2020 8:45 am
Forum: Computer Chess Club: General Topics
Topic: ** Nominations for Moderator Elections Now Open **
Replies: 1
Views: 996

Moderation policy

[Moderation] This seems a natural place for candidates in the CCC moderator elections to present their moderation policy. As this thread is locked, the candidates are invited to post their policy in a separate thread, PM me about it, and then I will move that posting into this thread. My moderation...
by hgm
Sat Oct 31, 2020 8:09 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Rustic vs. Shallow Blue: one of us is weird somehow
Replies: 18
Views: 396

Re: Rustic vs. Shallow Blue: one of us is weird somehow

My engines usually do IID, so I cannot just increase the alpha that was passed to them: the next internal depth iteration will have to start at the original alpha. So I have to remember the start_alpha, and reset alpha to it at the start of every depth iteration. And afterwards I can test for a fail...
by hgm
Sat Oct 31, 2020 7:40 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Principal Variation Search vs. Transposition Table
Replies: 17
Views: 537

Re: Principal Variation Search vs. Transposition Table

There is a huge confusion here, because people refer to first 'following the PV' as 'PVS', which actually means something entirely different. And it was also not made clear that when they want to follow 'the PV', they mean the PV of the previous iteration. And indeed, ideally the PV of the previous ...
by hgm
Fri Oct 30, 2020 7:25 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Engine with a Witch
Replies: 8
Views: 188

Re: Engine with a Witch

Indeed, but that doesn't require any change in the program. Fairy-Max is configurable through an fmax.ini file, and it is only a matter of adding a single line with a list of the possible move steps (16*dy+dx), and what these are allowed to do (slide, capture, non-capture). So it can do pretty much ...
by hgm
Fri Oct 30, 2020 4:59 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Engine with a Witch
Replies: 8
Views: 188

Re: Engine with a Witch

Hmm... I looked at the exact rules for the Witch, and it is a bit more involved than I thought. For one, the Witch is also transparent itself, for friendly pieces. So you would have to examine 9 squares rather than 8 for a Witch. But it doesn't make pieces transparent for itself. So you would have t...
by hgm
Fri Oct 30, 2020 4:35 pm
Forum: Computer Chess Club: General Topics
Topic: Question to Shut Ctf Down posters
Replies: 75
Views: 2190

Re: Question to Shut Ctf Down posters

Dutch idiom is often very close to English. It is just an invitation to view things in a wider perspective.
by hgm
Fri Oct 30, 2020 4:30 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Rustic vs. Shallow Blue: one of us is weird somehow
Replies: 18
Views: 396

Re: Rustic vs. Shallow Blue: one of us is weird somehow

That is really strange, as collecting info on the PV should not affect move choice at all. Problems of this type are indicative of using an uninitialized variable. Best way to debug this seems to find a position where the version with and without PV collection show a different result already at low ...
by hgm
Fri Oct 30, 2020 3:29 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Engine with a Witch
Replies: 8
Views: 188

Re: Engine with a Witch

The latest source is in my on-line git repository: http://hgm.nubati.net/cgi-bin/gitweb.cgi . Just download the latest 'snapshot' from there. The source code is in the file fairymax.c . The point where it would have to be changed is {if(t&&(t&16)==k)break; /* capture own */ The if() testst whether t...
by hgm
Fri Oct 30, 2020 3:13 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: How does an engine determine mate and stalemate?
Replies: 4
Views: 110

Re: How does an engine determine mate and stalemate?

Indeed, when you have determined that a move has a score that punishes the opponent's preceding move more than another move he is already certain of, there is no need to examine more moves to see if you can punish it harder. The jargon for this is a 'beta cutoff'. This is not the best you can do, ho...
by hgm
Fri Oct 30, 2020 2:43 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: How does an engine determine mate and stalemate?
Replies: 4
Views: 110

Re: How does an engine determine mate and stalemate?

The simplest way to do it is in the recursive search routine: * If one of the moves of the player on move captures the opponent King, that player wins, and you return the maximum score (let's call it +INF) * In the caller the score of the move reaching that position then shows up as -INF. Which you ...