mmt Vs. Ovyron (G4 D5 BG2)

Discussion of computer chess matches and engine tournaments.

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Ovyron
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by Ovyron »

zullil wrote: Mon Feb 24, 2020 12:11 am If it takes you days to find an optimal line of play in this setting, things can only be worse in "typical" positions
Nope, I found the optimal line within minutes. You can't do better than a line that mates the opponent 100% of the time. Anything to do with mating in fewer moves is unnecessary.

If you don't believe me, we can try it out, we play Zenmastur's position, I play moves that I found in 20 seconds (not the moves I have now) and you try to defend it. If with 20 seconds I beat any defense that you provide then it's optimal. Fewest moves to mate aren't optimal, they're overkill.
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by mmt »

1. g4 d5 2. Bg2 Bxg4 3. c4 c6 4. Qb3 e6 5. Qxb7 Nd7 6. Nc3 Ne7 7. cxd5 exd5 8. d4 Rb8 9. Qa6 Rb6 10. Qd3 Ng6 11. h3 Be6 12. Nf3 Bd6 13. h4 h5 14. b3 Nf6 15. Bg5 O-O 16. e3 Re8 17. Kf1 Bg4 18. Ne1 Bb4 19. Na4 Rb8 20. Nc2 Be7 21. f3 Be6 22. Nc5 Bc8 23. Kf2 Nd7 24. Ne6 Qa5 25. Bxe7 Rxe7 26. b4 Qb6 27. Ng5 Ba6 28. Qa3 Rbe8 29. Bf1

[d]4r1k1/p2nrpp1/bqp3n1/3p2Np/1P1P3P/Q3PP2/P1N2K2/R4B1R b - - 3 2
LC0's preferred move. It's at -2.28.
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by zullil »

Ovyron wrote: Mon Feb 24, 2020 12:32 am
zullil wrote: Mon Feb 24, 2020 12:11 am If it takes you days to find an optimal line of play in this setting, things can only be worse in "typical" positions
Nope, I found the optimal line within minutes. You can't do better than a line that mates the opponent 100% of the time. Anything to do with mating in fewer moves is unnecessary.

If you don't believe me, we can try it out, we play Zenmastur's position, I play moves that I found in 20 seconds (not the moves I have now) and you try to defend it. If with 20 seconds I beat any defense that you provide then it's optimal. Fewest moves to mate aren't optimal, they're overkill.
I might as well talk to a rock ...
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Ovyron
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by Ovyron »

zullil wrote: Mon Feb 24, 2020 1:45 am I might as well talk to a rock ...
Suppose that my analysis method allowed me to play perfect chess, by telling me magically if a position was drawn, won for white or won for black. All I'd need to do is check if the position after the move I'm going to make is lost and avoid it, or won if my opponent has blundered, and then all my moves are perfect chess moves. Would you still say that I needed better hardware?

Because, having access to such a thing wouldn't help me find the fastest mate, because all it'd tell me is that the position is winning, and all the moves that win, so I can ensure a win, but not the shortest win.

See how the shortest mate is useless and how abilities that help me play perfect chess are completely different? And how faster hardware to find that shortest mate is useless?

If you don't see it, no better hardware will help you see it, and I doubt you can play at my level despite your hardware. Your hardware allows you to find the fastest mate in a fraction of the time it takes me, yet you can't use it to play better chess, what a pity!
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by jp »

Ovyron wrote: Sun Feb 23, 2020 5:20 pm
jp wrote: Sun Feb 23, 2020 12:03 pm If a commercial engine like Fritz could get it wrong then, I don't know how people can argue that engines cannot now. (Of course, we are not assuming that they do get it wrong, either.)
The argument is that if it happens, it's a bug (unintended behavior by Fritz's developers, in this case), not how chess engines are meant to work.
It's a bad argument. Though it's useful in general to think about "bugs" as totally separate from algorithmic flaws, in this discussion that just waves away and excuses incorrect claims as "just a bug". We can't just assume this is something like a misplaced bracket.

Of course, we know how we'd like engines to behave. The question is whether they always do behave that way. This really isn't synonymous with basic alpha-beta, as you claim. (If, for example, the mistakes had been completely TB-related, then it might at least feel a little further away from the main engine function, though still bad.) For example, if it were just about basic alpha-beta, why would SF need that extra code you quoted as evidence SF is doing it properly?
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by Ovyron »

jp wrote: Mon Feb 24, 2020 4:00 am For example, if it were just about basic alpha-beta, why would SF need that extra code you quoted as evidence SF is doing it properly?
It isn't needed, it's there for convenience. Many engines don't know they're mating, and don't care, they just show some +100.00 score and are done with it, the only thing that matters is that they play winning moves.

Reporting mate is a feature added for user's convenience (so they can use the engine to check for mates instead of getting high scores) and for A/B engines there's only a single way to implement it. If you don't implement it in this way, then it's going to be buggy behavior, so if the engine reports a mate and it's not maximal (if the opponent defends perfectly then the engine can mate in at most n moves) it's a bug because that's not how the user expects the engine to behave.

The worst possible scenario is reporting a mate in 1 for a position that is a mate in 2, if that happens it's clearly a bug.
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by jp »

Ovyron wrote: Mon Feb 24, 2020 4:20 am
jp wrote: Mon Feb 24, 2020 4:00 am For example, if it were just about basic alpha-beta, why would SF need that extra code you quoted as evidence SF is doing it properly?
It isn't needed, it's there for convenience. Many engines don't know they're mating, and don't care, they just show some +100.00 score and are done with it, the only thing that matters is that they play winning moves.
You see, this is the point in long discussions where you start changing arguments, contradicting yourself, abandoning all logic, etc.

That engines (their authors, really) "don't care" is the exact point that Uri, I and others have been making, while you and Zenmastur have variously been insisting they "do care" and therefore find all "bugs", or, worse, insisting that correct mate announcements naturally come out of alpha-beta (which is what you were implying before you turned around 180 degrees here and talked about "convenience", "don't care", etc.).

It's mind-boggling. Just look back through this whole discussion. You have just flipped your arguments on their heads.
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by jp »

mmt wrote: Mon Feb 24, 2020 12:56 am 4r1k1/p2nrpp1/bqp3n1/3p2Np/1P1P3P/Q3PP2/P1N2K2/R4B1R b - - 3 2
LC0's preferred move. It's at -2.28.
Komodo 13.2, depth 31: -1.28 (... Bxf1).
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by Ovyron »

No, all this time I've been talking about A/B engines that report mate scores and how they behave or misbehave. It wouldn't have made sense for me to be talking about non-A/B engines or A/B engines that don't report mate scores, because then what I was saying wouldn't have made sense (it'd not have been about me being right or wrong, but about making sense, because if I'm talking about an engine reporting mate, of course I could not longer be referring to one that reports +100.00 scores instead of mates.)
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Re: mmt Vs. Ovyron (G4 D5 BG2)

Post by mmt »

if 29... Bxf1 then 30. Raxf1