31 Jan 12
Originally posted by tollehFirst thing I thought of was promoting to a knight. That seems also enough to win, no stalemate from the check with the black queen.
yes this is correct 🙂 funny thing is also that i analyzed this with an engine, and it doesnt find the correct move even with depth 26
31 Jan 12
1 edit
Originally posted by tollehI'm guessing you used Rybka which doesn't support underpromotion to bishop (an optimisation in the code). Other top engines find it immediately.
yes this is correct 🙂 funny thing is also that i analyzed this with an engine, and it doesnt find the correct move even with depth 26
I solved it myself through a process of elimination... can't do that... can't do that... so that only leaves...
31 Jan 12
Originally posted by VarenkaOut of interest, why doesn't Rybka support this? Why is eliminating a rule that may be your only way to win a game (as demonstrated above) an 'optimisation'?
I'm guessing you used Rybka which doesn't support underpromotion to bishop (an optimisation in the code). Other top engines find it immediately.
I solved it myself through a process of elimination... can't do that... can't do that... so that only leaves...
31 Jan 12
Originally posted by Rank outsiderhttp://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=1042
Out of interest, why doesn't Rybka support this? Why is eliminating a rule that may be your only way to win a game (as demonstrated above) an 'optimisation'?
Vasik Rajlich is the Rybka author so you can see his posts there.
31 Jan 12
Originally posted by VarenkaFunny attitude he has. Why disable some rules, because generally they are rare? En Passants are also rare...
http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=1042
Vasik Rajlich is the Rybka author so you can see his posts there.
A few of my games here on RHP I have underpromoted, because of the stalemate risque. So I don't see them as sooo rare after all.
31 Jan 12
Hi V.
I read that link. Quite funny. I like this bit.
"You must understand that Rybka will lose chess strength if Vas adds that option."
(adding under promotion to a Bishop as a valid option.)
OK coaches. New Rule No.103.
Do not teach your students how to under promote.
Doing so will make them weaker.
Is Rybka not a clone of another program? I know Rybka was stripped of all
it awards. Does the program it copied have the same trouble?
I know the earlier programs of Fritz had trouble finding simple mates in two
in certain positions.
This one stumps Fritz 6 (I think I have the mark correct.)
White to Play Mate in Two.
The solution is 1.Re1 Kxe1 2.Qd2 mate. Simply enough but Fritz failed.
Yet here. White to Play Mate in Two.
The same program finds the mate in 2 in a second. (it's the same solution 1.Re1 and Qd2 mate.)
31 Jan 12
Originally posted by FabianFnasI think it is only bishop underpromotion that is not covered. And in the above example, would not underpromotion to knight work?
Funny attitude he has. Why disable some rules, because generally they are rare? En Passants are also rare...
A few of my games here on RHP I have underpromoted, because of the stalemate risque. So I don't see them as sooo rare after all.
In fact, is there any real-life example of a game that anyone is aware of where underpromotion to a bishop is the only way to win?
One for Greenpawn I think.
(Loving the Kindle, by the way 😉)
31 Jan 12
Originally posted by Rank outsiderErr....winning with the knight does not look easy. But then again, I would have probably struggled with the bishop.
I think it is only bishop underpromotion that is not covered. And in the above example, would not underpromotion to knight work?
In fact, is there any real-life example of a game that anyone is aware of where underpromotion to a bishop is the only way to win?
One for Greenpawn I think.
(Loving the Kindle, by the way 😉)
31 Jan 12
Originally posted by greenpawn34There's a big debate that I'm not clued up on. I think the claim is that an early version of Rybka used some - not all - code from another engine called Fruit. I don't think Fruit has this bishop underpromotion issue but that doesn't settle the clone claim.
Is Rybka not a clone of another program? I know Rybka was stripped of all
it awards. Does the program it copied have the same trouble?