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The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 6:54 am
by MJMcCready
How did I go wrong here? What should I have done? I thought I had it won. I am black. Cinnamon 1.2c engine is my opponent, rated 1935
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 9:17 am
by LawrenceCooper
MJMcCready wrote: ↑Mon Dec 23, 2024 6:54 am
How did I go wrong here? What should I have done? I thought I had it won. I am black. Cinnamon 1.2c engine is my opponent, rated 1935
Hanging a rook with check looked unnecessary.
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 11:38 am
by Paul Cooksey
2...d5 is an improvement
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 12:44 pm
by Christopher Kreuzer
Is the final position actually drawn, or can Black evade the checks? Leaving the rook en prise is careless. Would be even more careless if the final position was still winning...
Does anyone know how computers 'limit' themselves to play to a 1935 (or any other) rating? I presume they do it in a different way to how humans would play 'generously' against e.g. a beginner they were trying to encourage to take up the game?
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 1:30 pm
by Christopher Kreuzer
Apparently:
https://www.chessprogramming.org/Cinnamon
Cinnamon 1.2 applied a kind of classical approach to generate ray-wise sliding piece attacks, captures and quiet moves. Cinnamon 2.0 already used line-wise occupancy lookups. Four pre-calculated attack arrays containing attack bitboards on ranks, files, diagonals and anti-diagonals were indexed by the square of the sliding piece, and the associated occupancy index of that line, determining the blockers affecting the attack set. Rather than to get the occupancy index from incremental updated rotated bitboards for each of the four line kinds, Cinnamon extracts line occupancies into a dense index range using multiplication and shift right, as mentioned in diagonals to rank or flip about the diagonal. The resulting 8-bit occupancy requires 512 KiB for all lookup tables, so considering the inner six bits would quarter the table sizes. In Cinnamon 2.3 the occupancy index may be computed by the PEXT instruction, if the executable is compiled with BMI2 enabled.
There is something hypnotic about that prose...
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 3:28 pm
by Mick Norris
Paul Cooksey wrote: ↑Mon Dec 23, 2024 11:38 am
2...d5 is an improvement
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 3:38 pm
by Matt Mackenzie
Paul Cooksey wrote: ↑Mon Dec 23, 2024 11:38 am
2...d5 is an improvement
Though not much of one
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 4:24 pm
by MJMcCready
Does it look like I pay enough attention to my opponents moves?
Re: The power of the St. Georges Defence but how did I let the win slip? Advice most welcome.
Posted: Mon Dec 23, 2024 8:31 pm
by John Upham
MJMcCready wrote: ↑Mon Dec 23, 2024 4:24 pm
Does it look like I pay enough attention to my opponents moves?
Yes