Cursed win at TCEC

[Ralph Stoesser]

FIDE rules are made from humans for humans, but not for pure engine competitions. In that sense they stay untouched by this proposal.

[hgm]

I thought I saw someone write in the threat that initially it was draw even without 50-move rule, and then Houdini started doing moves that would be sub-optimal in the chess variant without 50-move rule because it did not care, so that in the end it converted to a cursed win. I did not look at the game myself; that is more effort than I am willing to invest on this.

I think the TCEC rules are very clear in stating the 50-move rule applies. Whether it would make a better game when the 50-move rule was replaced by a more complex rule is another discussion. It is actually a hard problem. It is very unsatisfactory to introduce rules that are dependent on technological progress, in this case the availability of end-game tables. It is quite conceivable that engines will be able to generate the relevant slices of 9, 10 or 11-men EGT with many blocked Pawns on the fly. Suppose an engine that can do that claims it sees a mate-in-1000 with 900 moves to conversion in a 9-men position... What do you do now, after 50 reversible moves?

The 50-move rule is a real bitch. On the one hand you need something to force stubborn players (and none are more stubborn than computers...) into accepting a draw. OTOH, it is often difficult to define what progress is. This is especially problematic in games that forbid perpetual (= repetitive) checking, but easily allow 30 checks in a row before the possibilities to check without repeating are exhausted. Then the losing side can stall for 30 moves every time you do one move to make some progress. Which is especially painful in games where the eventual win comes by promoting a piece that can also move backwards. Because even if you would make only forward moves reset the ply counter, the piece could just be shuttled forward-backward to reset the counter without making any progress. So it becomes virtually impossible to define what progress is.

I guess the best solution would be this: a side that has a win can request a larger number of moves than 50 in order to achieve it. But if he does so, and doesn't manage to win (e.g. because the game converts to insufficient material, or runs into a repetition), he will be declared loser. That should be enough to discourage frivolous use, and limit extension requests for cases where the player indeed sees a certain win.

[syzygy]

To remove the stalemate rule would be a major change. Most chess studies would be worthless. The character of the game would change too much. Additionally it would result in a change of the FIDE rules, but nobody here proposes to change the FIDE rules. The proposal is to overrule the 50 move rule in case of

1) pure engine competition
2) a tablebase checkmate has been found in current position

First, how does that not change the FIDE rules?

Second, what means "a tablebase checkmate has been found in current position"?

In game 17, SF did not find a checkmate or a tablebase checkmate. Btw, what is the difference between "checkmate" and "tablebase checkmate"?

Perhaps you mean that the 50-move rule should be ignored in any position that somewhere in the world or in this universe by calculation has been determined to be a checkmate (for a chess-like game that is not FIDE chess) prior to the date that the TCEC game is played? Do you care at all whether the engines know about this calculation and have access to it? Do you care at all whether the TCEC adjudication mechanism has access to it?

Or do you mean that whatever the TCEC TB adjudication mechanism returns must be accepted as correct, whether the TBs it uses are faulty or not?

Third, I don't get why people are looking into changing a clear rule into something funny just to solve this problem when there is the very simple and correct solution of adjudicating to the correct result. It is trivial to look up the correct result of 5-piece positions. In addition, the engines are aware of the correct results and choose their moves having in mind the correct results.

[Ralph Stoesser]

1) Why should that change the FIDE rules? They stay exactly the same. The question should rather be why a piece of software should try to 100% conform to a set of rules that were created for human entities under special tournament conditions? Does it make sense? In all cases?

2) Again: Look at the ICCF rules.

10.Tablebase Adjudication

a. ICCF acknowledges some tablebases as valid for claiming win/draw/loss in positions solvable with the following tablebase: Convekta Ltd, which solves all positions with maximum 6 men. Each certified tablebase will be available on the ICCF Webserver system.

b. In case the tablebase shows a win that supersedes the 50 moves rule, the win will be awarded

3) For engine competition an inevitable mate should also take priority over a rule that has been created for human competitions under special thinking time constraints. Is that so hard to accept? What do you think why ICCF has such an adjucation rule that superseeds the 50 move draw rule? What is the idea behind that horrible FIDE rules derision? Note that this rule is from January 2016. So they could have used "correct" tablebases. Your tablebases are not so universally important as you might think. They are usefull in all cases where following the FIDE rules is important: Study of FIDE games with computer assistance and perhaps in case an engine should ever again participate in an human FIDE tournament.

[syzygy]

1) Why should that change the FIDE rules?

Do you not realise that the 50-move rule is a FIDE rule?
http://www.fide.com/fide/handbook.html? ... ew=article
Article 5.2 e)

The question should rather be why a piece of software should try to 100% conform to a set of rules that were created for human entities under special tournament conditions? Does it make sense? In all cases?

We've been through this 10 times now. Yes, it makes sense because without it engine-engine games last thousands of moves. And no, a rule like "ignore the 50-move rule when I like it" simply does not work.

And I will repeat this: applying the same rules to human-human, human-engine and engine-engine games poses no problems whatsoever. And why fix a problem that does not exist...

2) Again: Look at the ICCF rules.

At least they have put it in the rules.

But the rule is stupid.

First, why do they have it? Answer: because they thought there was no alternative. They thought TBs necessarily ignore the 50-move rule. That is wrong, but they did not know better. With proper TBs, there is no problem and there is no reason to change the game to fit the shortcomings of TBs.

Second, do you realise what they have done? They let Convekta decide the outcome of games. They "certified" the Convekta TBs... do you think they checked that those TBs are correct? Certainly they did not. They just placed blind trust in the correctness of what Convekta is offering.

3) For engine competition an inevitable mate should also take priority over a rule that has been created for human competitions under special thinking time constraints. Is that so hard to accept?

Do you know the meaning of what you are saying?

How do you know that a position with 20 pieces left on the board and which is approaching 50 moves has no "inevitable mate"? You do not know that. The engines may seem unable to make progress and they may actually be unable to make progress, but we have no way of knowing that there is no "inevitable mate". The concept you are proposing is broken. Unless you can prove a draw, which practically will never be possible, you will have to play out the games until electricity runs out.

Note that this rule is from January 2016.

Wrong again. At least try to get the facts rights...

The rule took effect on 1 January 2014. Long before that date I had added Syzygy50MoveRule to my SF TB-fork, which fully complies with their silly rule. My TBs happen to include cursed and real wins, so there is no problem whatsoever. But that does not stop the ICCF rule from being misguided.

And ICCF picked 6-men. Why 6? Why not 7? Now if an engine has 7-piece TBs you still can't trust the result.

[Lyudmil Tsvetkov]

I thought I saw someone write in the threat that initially it was draw even without 50-move rule, and then Houdini started doing moves that would be sub-optimal in the chess variant without 50-move rule because it did not care, so that in the end it converted to a cursed win. I did not look at the game myself; that is more effort than I am willing to invest on this.

I think the TCEC rules are very clear in stating the 50-move rule applies. Whether it would make a better game when the 50-move rule was replaced by a more complex rule is another discussion. It is actually a hard problem. It is very unsatisfactory to introduce rules that are dependent on technological progress, in this case the availability of end-game tables. It is quite conceivable that engines will be able to generate the relevant slices of 9, 10 or 11-men EGT with many blocked Pawns on the fly. Suppose an engine that can do that claims it sees a mate-in-1000 with 900 moves to conversion in a 9-men position... What do you do now, after 50 reversible moves?

The 50-move rule is a real bitch. On the one hand you need something to force stubborn players (and none are more stubborn than computers...) into accepting a draw. OTOH, it is often difficult to define what progress is. This is especially problematic in games that forbid perpetual (= repetitive) checking, but easily allow 30 checks in a row before the possibilities to check without repeating are exhausted. Then the losing side can stall for 30 moves every time you do one move to make some progress. Which is especially painful in games where the eventual win comes by promoting a piece that can also move backwards. Because even if you would make only forward moves reset the ply counter, the piece could just be shuttled forward-backward to reset the counter without making any progress. So it becomes virtually impossible to define what progress is.

I guess the best solution would be this: a side that has a win can request a larger number of moves than 50 in order to achieve it. But if he does so, and doesn't manage to win (e.g. because the game converts to insufficient material, or runs into a repetition), he will be declared loser. That should be enough to discourage frivolous use, and limit extension requests for cases where the player indeed sees a certain win.

Rules should be changed, when they are unjust, which is precisely the current case.

Whe you have a law, that is unjust, and you have to decide based on that law, what you do: take a decision following the unjust law, or change the law to accomodate justice? Any decent person would prefer to change the law.

The game was already a white win: SF had been showing 105cps from the early mg, Houdini some 80cps. That is a win, however you would like to look at it. Why penalise SF because some tablebase rule artificially prunes the mating sequence, rendering it a draw instead? The claim that H went for the tb position because it saw it is 0.0, and otherwise black had better options, is simply wrong, as, most probably white had a win throughout. It was KQPP vs krbb, the3 pieces are much stronger than the queen, but apart from having 2 passers, white also has the additional advantages that they are 1) connected, 1) very advanced - 5th and 6th rank, 3) provide the white king a shelter, 4) the white king is very advanced, supporting its passers, 5) the black king lacks pawn shelter. Not sufficient? I guess the white position, barring a miracle, is simply won throughout, tbs or not, so why penalise the stronger engine and the won game?

Concerning your ridiculous claim that KP vs K with stalemate position also favours white, but is still a draw, how on earth you compare this absurd position with the tbs mate? In KP vs k and stalemate, the position is simply draw, as there is no mate, while in the referenced TCEC position, this is a win, there is mate. If you agree that DRAW=WIN, then you are perfectly rigth, otherwise, why you make such impossible claims? Is DRAW=WIN?

[Lyudmil Tsvetkov]

Third, I don't get why people are looking into changing a clear rule into something funny just to solve this problem when there is the very simple and correct solution of adjudicating to the correct result.

Many reasons:

1) the rule is unjust, it penalises the side having a win, you artificially transform a win into a draw.
2) what is the purpose of wdl, when, according to current rules, W=D?
3) tablebase mates in more than 50 moves are relatively frequent, there are at least 500 of those discovered as of now, certainly more will be added later; why take a blindfold stance, claiming those are all draws?
4) my artistic sense gets bitterly offended, when all side's efforts and an objectively won position are declared a draw; I guess everyone else's artistic sense gets offended too?
5) rule is simple to implement and without detriment to the overall game development; you split the rule into 2 portions, one concerning the general 50-moves rule for the standard game situation, not to make the game too long, and a second one providing for the specific case of pawnless endgames, where the 50-moves rule will be adjusted to 100-move rule or higher, to accomodate the won endgames. Very simple.
6) Rules change with progress. Until we knew there are tbs wins longer than 50 moves, the 50-move rule was adequate, now, when we know there are such longer wins, the 50-move rule becomes outdated and should be changed.

[hgm]

Rules should be changed, when they are unjust, which is precisely the current case.

Rules that are changed as one sees fit whenever they have to be applied do not qualify as rules. One decides upon rules in advance, and makes all involved aware of those. In particular one does not penalize participants for obeying rules they were told to obey, because as an afterthought you think the agreed-upon rules are bad or sub-optimal. That seem pretty elementary properties of the rule concept.

Whe you have a law, that is unjust, and you have to decide based on that law, what you do: take a decision following the unjust law, or change the law to accomodate justice? Any decent person would prefer to change the law.

There is nothing 'unjust' about the 50-move rule, anymore than that it is unjust that a Bishop can only reach squares of one color, or that stalemate is a draw, or that in case of a 3-fold repetition the side with more material doesn't win.

The game was already a white win: SF had been showing 105cps from the early mg, Houdini some 80cps. That is a win, however you would like to look at it.

That is total bullshit. I have seen Stockfish and Houdini score positions as +1150cp, and still lose.

Why penalise SF because some tablebase rule artificially prunes the mating sequence, rendering it a draw instead?

Because that 'artificial' rule was the one adopted for the tourney seems a pretty good reason to enforce it. To me, at least...

Concerning your ridiculous claim that KP vs K with stalemate position also favours white, but is still a draw, how on earth you compare this absurd position with the tbs mate? In KP vs k and stalemate, the position is simply draw, as there is no mate, while in the referenced TCEC position, this is a win, there is mate. If you agree that DRAW=WIN, then you are perfectly rigth, otherwise, why you make such impossible claims? Is DRAW=WIN?

Not draw=win, but stalemate=win. Logically most stalemates are wins, because the stalemated side is forced by zugzwang to move his King into check, upon which it will be captured and he loses. It is only a draw because of the artificial FIDE rule that says it is a draw. But in fact it is just a position where you cannot avoid your King will be captured on the next turn. So this rule unfairly robs the opponent of the opportunity to capture the King, by terminating the game one half-move before it with an artificial draw result.

[Evert]

Rules should be changed, when they are unjust, which is precisely the current case.

The rule in unjust in your opinion, which is not fact.

The game was already a white win: SF had been showing 105cps from the early mg, Houdini some 80cps. That is a win, however you would like to look at it.

So evaluating a position at +0.80 constitutes a win? This is new to me.
I for one don't think this is a rule that should be adopted.

Why penalise SF because some tablebase rule artificially prunes the mating sequence, rendering it a draw instead?

Tablebases have nothing to do with it other than telling you with absolute certainty what the outcome of perfect play under a set of rules would be.
In this case the outcome is different if the 50-move rule is observed and if it is not.

So is the 50 move rule observed? Yes, it is. Is the position a draw under the 50 move rule assuming perfect play by both sides? Yes, it is.

Do you like the 50 move rule? Apparently not. That's an entirely different discussion though.

The claim that H went for the tb position because it saw it is 0.0, and otherwise black had better options, is simply wrong, as, most probably white had a win throughout.

Proof it.
You don't get away with saying you can "probably" proof it.

Note that Stockfish played by the same rules and had access to the same table bases as Houdini. So if Stockfish had a way to salvage the win, it missed it and squandered the point. That's all in the game.

Concerning your ridiculous claim that KP vs K with stalemate position also favours white, but is still a draw, how on earth you compare this absurd position with the tbs mate? In KP vs k and stalemate, the position is simply draw, as there is no mate,

Yeah, there is. Stalemate, which the rules say is a draw. The rules of chess are not set in stone and can and historically have changed. Stalemate used to be a win. Hell, baring the enemy king used to win the game.
Yet under the current rules, the position is a draw. The 50-move rule is really no different.

while in the referenced TCEC position, this is a win, there is mate.

Yeah, but unfortunately not within 50 moves. So the win is cursed.

[Evert]

1) the rule is unjust, it penalises the side having a win, you artificially transform a win into a draw.

It certainly makes the game more draw-ish, and you're perfectly allowed to make a chess variant that doesn't employ the 50 move rule. It'll be a different game, with different strategy in the late end game.

Let me ask you this though: why is it more unjust to rob the side with a win of their win, than to rob the side that can escape with a draw of their escape?

2) what is the purpose of wdl, when, according to current rules, W=D?

Where does it say that?

3) tablebase mates in more than 50 moves are relatively frequent, there are at least 500 of those discovered as of now, certainly more will be added later; why take a blindfold stance, claiming those are all draws?

Because adding exceptions for all of them is unmanageable?
They used to have exceptions when tablebases first showed long wins in certain end games, and quickly realised that allowing these is a Pandora's box that leads to so many exceptions that the whole thing becomes unwieldy.

4) my artistic sense gets bitterly offended, when all side's efforts and an objectively won position are declared a draw; I guess everyone else's artistic sense gets offended too?

Objectively won under a set of rules that you prefer, but which are not the rules under which the game is played.
It's important to understand that "Chess" does not refer to one game. It refers to a family of (closely) related games with rules that are similar but may differ in subtle (or not-so-subtle) ways. Chess played under FIDE rules is a different game from Chess played under Correspondence rules. The rules for problems are different again.

5) rule is simple to implement and without detriment to the overall game development; you split the rule into 2 portions, one concerning the general 50-moves rule for the standard game situation, not to make the game too long, and a second one providing for the specific case of pawnless endgames, where the 50-moves rule will be adjusted to 100-move rule or higher, to accomodate the won endgames. Very simple.

Makruk has something like that, but the other way around. If you find yourself in a pawnless endgame and still have two rooks remaining, you have at best 4 moves to mate the enemy king (fewer if you have more material remaining). Hope you considered that before capturing that last pawn!
This deeply affects strategy in the end game.

Now, you're perfectly agreed to make a chess variant that uses your rule as an alternative to the 50-move rule. Knock yourself out. If it proofs to be popular, it may replace FIDE Chess eventually.

6) Rules change with progress. Until we knew there are tbs wins longer than 50 moves, the 50-move rule was adequate, now, when we know there are such longer wins, the 50-move rule becomes outdated and should be changed.

Why?
Because you prefer that? Not all of us share your personal preference.