Search found 16793 matches

by bob
Tue May 07, 2019 4:00 am
Forum: Computer Chess Club: General Topics
Topic: Authors of chess engines getting crushed by their creations
Replies: 17
Views: 2459

Re: Authors of chess engines getting crushed by their creations

Crap. Meant to write "have not been gone, am not coming back." That is, I never left. :) just haven't had much to say. It's amazing how busy life gets when you own a boat, an RV, automobiles, house, have family, travel, most everything is "do it yourself" and so forth. Sometimes I am busier now than...
by bob
Sun May 05, 2019 10:26 pm
Forum: Computer Chess Club: General Topics
Topic: Authors of chess engines getting crushed by their creations
Replies: 17
Views: 2459

Re: Authors of chess engines getting crushed by their creations

Wasn't intending to make this anything about me. However, for the record, my first chess program played its first move in very late 1968. I was a computer science major at the University of Southern Mississippi and star trek / spock / computer chess had already caught my interest. There was practica...
by bob
Sat May 04, 2019 5:41 pm
Forum: Computer Chess Club: General Topics
Topic: Authors of chess engines getting crushed by their creations
Replies: 17
Views: 2459

Re: Authors of chess engines getting crushed by their creations

Not sure this is "news". In the early 80's, I might win one out of 100 games against Cray Blitz, yet our ratings were pretty equal in terms of USCF. 5 years later, that was zero out of 100. Been that way all the way through current Crafty. It is really easy to develop an engine that beats you trivia...
by bob
Sat Nov 24, 2018 3:04 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: adding an existing key to the hashtable
Replies: 9
Views: 1692

Re: adding an existing key to the hashtable

Here's the reason for overwriting. Apparently whatever is there was not good enough to terminate the search at the start of this position, so what's the point of saving something that didn't work when you now have something that is correct and useful?? IE exactly what HGM said but with fewer words.....
by bob
Fri Nov 16, 2018 4:47 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Any Fortran coder ?
Replies: 26
Views: 4357

Re: Any Fortran coder ?

Recursion has worked for a long time now. One thing to avoid is a 2d array, use a 1d vector instead. Otherwise every array access ends up with an integer multiply buried in the middle of the address calculation. Otherwise it will work fine. The language is a bit of a mismatch for chess but I used it...
by bob
Wed Oct 03, 2018 6:17 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Rebel Book Draw?
Replies: 17
Views: 3312

Re: Rebel Book Draw?

This is a problem you have to fix. If your opponent plays a move that "undoes" one of his recent moves (or his most recent move most commonly) then you will find that position in your book if you are not careful to recognize the 2-fold repetition. My fix was to simply ignore a book move that repeats...
by bob
Sun Sep 23, 2018 4:59 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: about speed et profiling tools
Replies: 16
Views: 3122

Re: about speed et profiling tools

Another thought. NPS is highest when you do a pure minimax search. You don't waste any computation effort generating moves or doing other things that cost computational effort. As you improve ordering, you begin to see NPS drop because in lots of positions you just search one move and throw the rest...
by bob
Tue Aug 14, 2018 9:03 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: A more interesting question about GPU verses CPU
Replies: 18
Views: 4585

Re: A more interesting question about GPU verses CPU

To 'compare' algorithms you should first define a metric for algorithmic complexity. You seem to focus (completely arbitrarily) on the number of multiplications. One might just as well only consider the number of branches. With the same number of branches per second, Stockfish would not be a match ...
by bob
Tue Aug 14, 2018 8:52 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Time Management and Move Selection
Replies: 14
Views: 3540

Re: Time Management and Move Selection

My current "easy move" approach is really just a "easier/harder" approach. If things are stable, the situation looks "easier". If things are unstable, the situation looks "harder". That degree of stability can make the search move significantly faster, or significantly slower. Very "un-computer-like...
by bob
Tue Aug 14, 2018 4:18 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Attacks From table
Replies: 12
Views: 3658

Re: Attacks From table

unless you have a power of 2 size, a table lookup is going to include a multiply. Shift and add really don't count in a super-scalar architecture. I don't think there is anything to gain here. I used to do what Slate and Atkin did. Maintained an array of attacks. One showing all squares attacked fro...