Search found 419 matches

by D Sceviour
Sun Jun 23, 2019 6:23 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: FRC / Chess960 -- Some Lessons I Learned
Replies: 18
Views: 658

Re: FRC / Chess960 -- Some Lessons I Learned

[d]5rkr/8/8/8/8/8/8/RKR5 w - - 0 1 Castling is never allowed when you have no castling rights! Not sure what you mean. Do you mean no "KQkq" included in the fen? The FRC rules require that the king has to sit between two rooks. Perhaps the answer is no, because no pieces can lie between the rook an...
by D Sceviour
Sun Jun 23, 2019 4:37 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: FRC / Chess960 -- Some Lessons I Learned
Replies: 18
Views: 658

Re: FRC / Chess960 -- Some Lessons I Learned

What would be the final castling positions for this initial FRC position? Is queen side castling allowed?

[d]5rkr/8/8/8/8/8/8/RKR5 w - - 0 1
by D Sceviour
Tue Jun 11, 2019 3:55 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: The Poor Man's KP Bitbase
Replies: 5
Views: 497

Re: The Poor Man's KP Bitbase

This KP bitbase version updates a few more draw positions. Some test positions are included. The extra draws will not make much difference. The strength of the KP bitbase is in its resiliency and residency, and not its completeness. The idea is to prune known positional draws and to reduce nodes on ...
by D Sceviour
Tue Jun 11, 2019 12:12 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using evaluation hash score as current bestscore (initial guess)
Replies: 13
Views: 685

Re: Using evaluation hash score as current bestscore (initial guess)

upper hash < static - use the lower score upper hash > static - could still be a safe prune lower hash < static - looks like a safe prune lower hash > static - worth extending so make best_score = hash_score - to raise cutoff value and re-look at the position a little wider. use the higher score
by D Sceviour
Mon Jun 10, 2019 1:36 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: The Poor Man's KP Bitbase
Replies: 5
Views: 497

Re: The Poor Man's KP Bitbase

Notice that for the first two possibilities, the position of the strong king is irrelevant. The draw only depends on the position of the weak black king. We can almost solve the entire KPK ending without knowing the position of the white king! For example, in the following position the white king c...
by D Sceviour
Mon Jun 10, 2019 11:44 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: The Poor Man's KP Bitbase
Replies: 5
Views: 497

Re: The Poor Man's KP Bitbase

Just a question : in your code, kingsq is the square of the losing king right ? Hello Dany, Yes. The position of the winning king is always ignored! Does the kp table is filled when you run the engine? Yes, the initialization code is very fast - in pica seconds? :-) Sq-8 is the square in front, rig...
by D Sceviour
Fri Jun 07, 2019 12:54 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using evaluation hash score as current bestscore (initial guess)
Replies: 13
Views: 685

Re: Using evaluation hash score as current bestscore (initial guess)

Indeed, I understand well why and how those scores are used, I wonder how they can be used the same way, one being an eval score (probably on a board with hanging pieces !) and the other being a more correct search score. I don't get how the same pruning margins can be used with both ? It is not cl...
by D Sceviour
Fri Jun 07, 2019 1:05 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: The Poor Man's KP Bitbase
Replies: 5
Views: 497

The Poor Man's KP Bitbase

Why use the poor man's king-pawn (KP) bitbase? First, the bitbase is only 3K and thus very easy on resources. It could be compressed even further to 1.5K, but 3K is small enough to easily fit into the modern hardware cache. More compression may not be desirable because it will require extra decompre...
by D Sceviour
Thu Jun 06, 2019 10:53 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using evaluation hash score as current bestscore (initial guess)
Replies: 13
Views: 685

Re: Using evaluation hash score as current bestscore (initial guess)

You will often see a needed estimate for the score of a move. If the move is already in the hash table, then that is used as the estimate. If the move is not in the hash, then eval() is called to create an estimate. Usually this is used for pruning decisions {typically in null move processing} rath...
by D Sceviour
Thu Jun 06, 2019 9:39 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using evaluation hash score as current bestscore (initial guess)
Replies: 13
Views: 685

Re: Using evaluation hash score as current bestscore (initial guess)

It may be that we want a static evaluation to determine whether the position is improving. This is how various selective searches can make comparisons. The hash score is not effective to determine if the position is improving from the previous position since it represents a bound that may be higher ...