Search found 18434 matches

by hgm
Sun May 17, 2020 5:56 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: sort every moves or pickNext
Replies: 14
Views: 722

Re: sort every moves or pickNext

True. But some engines use a reduction that is dependent on the order, and randomly ordering the late moves might make that less effective.

Besides, even picking two moves could already be slower than the binned sorting.
by hgm
Sun May 17, 2020 11:19 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: sort every moves or pickNext
Replies: 14
Views: 722

Re: sort every moves or pickNext

I often have to deal with variants where there are far more than 100 moves. But my preferred sorting method for non-captures is just binning the moves by relative history score. That is, when updating the history table you keep track of the maximum history value. And I keep history scores as floats....
by hgm
Sun May 17, 2020 10:12 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: sort every moves or pickNext
Replies: 14
Views: 722

Re: sort every moves or pickNext

Sorting by picking the best every time is an O(N^2) process, which can get pretty slow if there are many moves (like there typically would be for non-captures). Using quick sort for sorting the whole lot at one is only O(N*log(N)), which is significantly less work if N is large. The picking speculat...
by hgm
Sun May 17, 2020 9:38 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: On-line engine blitz tourney May
Replies: 25
Views: 979

Re: On-line engine blitz tourney May

The 'Has Own Book' option is not persistent, because it is assumed to be an engine-dependent thing, and next time you might start up WinBoard with a different engine. So it seemed more logical to always start at the default, assuming the engine has its own book. (Also to maintain backward compatibil...
by hgm
Sat May 16, 2020 6:02 pm
Forum: Computer Chess Club: General Topics
Topic: Earliest chess engines that have features of AB pruning?
Replies: 5
Views: 423

Re: Earliest chess engines that have features of AB pruning?

Alpha-beta pruning was already described in elementary textbooks for AI courses when I was a math student in 1976. BTW, human chess players have used it far before computers could play chess, even though they don't know it. If you ask a chess player that has been thinking about a position why he is ...
by hgm
Sat May 16, 2020 5:50 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: On-line engine blitz tourney May
Replies: 25
Views: 979

Re: On-line engine blitz tourney May

Sounds like timeseal crashed. XBoard connects to the icshelper through a pipe. Timeseal is basically a tellnet terminal that piggybacks time stamps on the transmitted data.
by hgm
Fri May 15, 2020 12:58 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: On-line engine blitz tourney May
Replies: 25
Views: 979

Re: On-line engine blitz tourney May

Running engines on an ICS through XBoard is known as 'zippy mode' (for historic reasons). But you have to be careful, because including that mode in XBoard requires a compile option, which not all Linux distro maintainers might have switched on. So it is best to install XBoard from source, using the...
by hgm
Thu May 14, 2020 9:39 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Null move in TT
Replies: 6
Views: 445

Re: Null move in TT

You can just make the move in the TT entry 'invalid'. If the draft of the entry was not enough for a hash cutoff, the search would start with a null-move anyway. So there is no need to tell any prober that he has to start searching a null move first. In fact you can detect the case by the fact that ...
by hgm
Thu May 14, 2020 9:26 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Score "no pawns" question
Replies: 7
Views: 379

Re: Score "no pawns" question

Indeed, that is the "minor ahead (i.e. +3) is not enough" rule. In that case a factor 0.5 is not nearly enough, it will almost always be a dead draw. The factor 0.5 is good for cases like KRRKNNP, where you have a good winning chance, but where it is much more difficult than when you would be 2 Pawn...
by hgm
Wed May 13, 2020 8:00 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Score "no pawns" question
Replies: 7
Views: 379

Re: Score "no pawns" question

Using an additive penalty for this is no good. You will either grossly overestimate KBK or KPP(P)KB. For one, only the side that is ahead suffers from having no Pawns; if your aim is to defend the draw you don't care much whether you have mating potential yourself. The better method is to apply a mu...