Does anyone know of a game that was drawn under the mandatory 75 move rule?

didn't know that

Likewise, always though it was 50 regardless. I guess that makes it much easier for NB v. K or NN v. KP

It's 50 moves before you can claim a draw, after 75 moves it is automatic. For instance a computer interface might draw your game without anyone's request or consent after 75 moves without capture or pawn move. The same relationship exists for repetition draws after 3 and 5 repetitions.

Many computer interfaces do not abide by the FIDE chess rules. I suppose they are happy to live as outlaws which is considered an honorary title in some regions.

See post #254

yup its right

It is 50 right?

Logest game ever played in chess history by gm is 236 and it was drawn under 100.move rule 

It was then reduced to 50.move rull

So the endless discussion about the rules is still going on. If you just used my interpretation you wouldn't have these issues. You can't make legal moves in a stalemate and checkmate position, but that is not because they are "end positions". It is a direct consequence of the definition of checkmate and stalemate. If your king is under attack, then you have to make a move to break that attack and no such move exists if you are checkmated. Also you can make legal moves in a dead position or after 5-rep. We have discussed this before. Just follow my interpretation.

@Numquam:

Btw, the current discussion has shifted to the "legality of moves" which has effect on the eval of dead positions but not directly in relations to 75M or 5REP. I have written these notes because they are of great interest in the field of composition where the situation is much more complicated. Someone outside our little group will be reading them.

I follow no particular interpretation or opinion, I follow the theory for sequential move games. The conditions "end position" and "the on-move player has no legal move" are equivalent. The designation "end position" follows from the unavailability of a legal move by the on-move player which includes the player "having lost the right to play" for instance after a draw agreement. I discussed that in the previous long post under the intensional properties of legal moves. In this concept, moves can only be legal when playable within all of the available context of a game situation - not just in its diagram or as stand-alone piece geometries.

For checkmate and stalemate the  "legal move" situation is rather simple but still requires a look-ahead analysis - you must see that no candidate move saves your king. The "king attack" part is only required to distinguish checkmate from stalemate; otherwise it is simply the unavailability of a legal move.

The latter is also true for dead positions with the understanding that the dead rule effectively says that a move can only be played (= is legal) when there is a "possible checkmate" ahead - which is more or less algorithmically establishable. Just as for checkmate and stalemate the legal moves only matter when the position is not dead. In all other cases there is no need to permit legality of moves after end positions though it may be a handy tool for analyzing the situation. All means are allowed when simulating or analyzing.

Case: [this may be a case MARattigan tried to make but which I didn't originally get] A really interesting situation is the following. Assume the only way to escape from a checkmate is a move which clearly leads to a dead position. Corollary: the position is already dead before the move. But that would render the move "illegal". And when it is "illegal" then you are checkmated - king under attack and no legal move left.

Cause: The cause of this apparent contradiction is that the dead rule looks for checkmates in the future while the checkmate rule applies to the present position. This can lead to the simulataneous validation of 2 different game scores - win and draw. We know that the draw is the correct one but I haven't found the proper formal justification yet. Think about it.

You follow your own definition of legal move. As you may know FIDE has defined legal move as: "A move is legal when all the relevant requirements of Articles 3.1 – 3.9 have been fulfilled." So to me it is clear that it doesn't matter if the position is an end position, since there is no reference to Article 5 in Articles 3.1-3.9. The existence of a legal move does not imply that you are allowed to play that move. We had a similar disagreement about the dead draw rule (or was it MARattigan?). I believe you said that the series of legal moves leading to checkmate should not lead to a draw due to the 75-move or 5-REP rule.

Whoever made that case, that is a good find. I don't see a way to reason that it is a draw using the FIDE rules, if I use your definition of a legal move. You may say that the FIDE rules aren't properly formulated, but I think they have my interpretation in mind when they talk about legal moves.

It's not my own definition for "legal move" though game theory does not generally speak of "legal" and "illegal" moves - just of "moves". The idea of playing an "illegal move" is unthinkable in a mathematical system so it does not care to qualify a move as legal either.

You missed the points in my long post regarding definitions. The FIDE definition of legal moves in article 3 is only extensional and incomplete. All moves in all sequential move games share a number of categorical properties which are not specific to any particular choice of game like chess. For instance the fact that legal moves must always be played by the player on-move. That is required to prevent deviant interpretations such as that "a series of legal moves" need not be played by alternate colors. Also that a legal move must always be playable as I addressed in my post as well. Beyond article 5.2.2 there is not a single article that suggests that legal moves need not be playable. It would be very peculiar that FIDE intended to change that part of the "legal move" definition with the introduction of dead positions without making any mention of that highly impactful decision. Of course they didn't. Any storyline is better than that one - including FIDE incompetence.

The adjective "legal" has a natural language significance which goes beyond what FIDE likes or does not like to define. This is the case for many uses of the word "legal" in real life.. It refers to any amount of laws and regulations impacting the legitimacy of a formal activity such as running a business. So it is in chess though fortunately a bit less intricate.

"End positions" like "starting positions" are an integral part of sequential move game theory. It doesn't matter one bit whether FIDE addresses them or not under those names. They are there and they are implemented in the rules in some way or otherwise nobody would understand what makes games start or end.

The points regarding 75M and 5REP in combination with death remain unresolved because they are "relatively" independent from legal move definitions. Since death analysis depends on "simulated lines of play" there is no certainty that FIDE wanted these rules to figure in the simulations. IMO, the default assumption should be that they are active but I wouldn't bet that is what FIDE intended.

I read enough of the long posts about legal moves to understand that you use a definition of legal move which is not in the FIDE handbook and you argue that the FIDE definition is incomplete. In my opinion you make it way too complicated. If you stick to the more simple FIDE definition and don't include other aspects in the definition of legal move, then you have less issues.

For example: is a move suddenly illegal when you run out of time? What if you run out of time while your king is under attack? Is that a checkmate, because you can't make any legal moves? And if we read Article 6.9, then we would conclude that any other position is a draw, because the players can't play any series of legal moves leading to checkmate (unless you include series where they don't move alternately).

Therefore it is best to stick to the simplest definition of legal moves and don't include the act of moving or the time left on the clock into the definition. The term "legal" can have lots of different meanings in different contexts. So I would base my definition on what is written in the rules and anything else is not part of a "legal move". 

I will focus on the point towering over the whole discussion. Article 5.2.2 says after death confirmation:

"The game is said to end in a ‘dead position’. This immediately ends the game."

Here is the address of FIDE to an end position. The critical point is that where the game ends, the authority of FIDE rules ends. When the position under investigation is indeed dead then you can not only not play (il)legal moves, but everything connected with the game has ended - your opponent, the board, the pieces, the rules, the arbiter and you yourself as a game participant. When the game ends, the chess universe ends. It's like deporting an unwanted individual over the mexican border. You can throw him out but you can't direct him to go to Mexico city or any other place of your liking. Not your authority.

This is extraordinarily fundamental and not really negotiable. Mathematicicans bump into similar phenomena regularly in axiomatic systems. Gödel's sentence is the best known example. It can't be resolved inside Peano arithmetic; it demands a model which plays the same role as the procedure for analytical move analysis in dead positions. The solution is literally "out of the box".

So even if FIDE explicitly orders the moves to be legal beyond the game end then it's simply an act of howling at the moon. Nobody listens, nobody is impressed, nobody cares. They have no license to mine the moon.

The reason I object to any other approach to the legal move definition has a great deal to do with the composition domain. Once you let go of "legal moves" as "playable moves" all hell breaks lose there. People will start telling you all kinds of moves are now suddenly legal but unfortunately unplayable - and they mean something different with unplayable than a game player would! So I will not compromise here.

There is a midway point which permits viewing the after death move series as "legal but unplayable" from one side and as "illegal and therefore unplayable" from the other. What the articles 5.2.2. and 6.9 try to relay is the running of a simulation. Inside the simulation the moves are both legal and playable because the dead position restriction is removed as part of the simulation rules. Since the purpose of the simulation is only to produce a verdict on the game state, its operation does not affect the appreciation of the same moves outside the simulation where they remain illegal and unplayable (if the position is dead).

The other - standard logical - approach is RAA (reduction ad absurdum) which is not unlike the simulation. By assuming the after death move series is legal, you prove a contradiction - no checkmate can be found - and conclude your assumption was wrong. This is considered a valid logical method except by intuitionists.

One more note on the status of the definition of "legal moves". Article 3 does not define "legal moves", it defines "the legal moves in chess" which only validates a particular extensional list of choices. The expression "legal moves" retains all of its common natural and legal connotations - especially those relevant to the category of sequential move games. For instance, everyone will understand that a move played out of turn is illegal. One might argue that move alternation is part of the game flow and not part of the move definition but that raises questions on the meaning of "a series of legal moves". Where is the game flow if not in the "legal moves"? MARattigan has an answer to that question!

The definition of "legal moves" that FIDE uses indeed implies that they are not necessarily playable. It may have been better to use another term instead, but that would probably cause unnecessary confusion. You could call them "potential position change". But most chess players would not call a move illegal just because the position is a dead draw or when there is no time left on the clock. For example an analysis of a game contains series of legal moves which were never played. It is entirely normal to use the term "legal moves" for moves which were never played on the board.

This proving technique does not fix the issue you described before when the only way to escape from a checkmate is a move which leads to a dead position.

No I didn't make the case, but the idea is brilliant. 

It appears undeniable that the best move in this White to play position is Qd7# 1½ - ½ (which I have overlooked countless times).

It's worth noting that the Nalimov and Syzygy EGTBs fail to find this.

(If the move is played with the left hand and the players shake hands with the right and both resign simultaneously with the release of the queen on d7 could the arbiter be persuaded to award  3 - 2?)

Several points:

Regarding your parenthesised caveat, the players can't play a series of moves where they don't move alternately because that would violate art 1.2:

1.2 The player with the light-coloured pieces (White) makes the first move, then the players move alternately, with the player with the dark-coloured pieces (Black) making the next move

and neither can they play play a series of moves in which the colours of the pieces moved do not alternate because that would violate art. 4.3 and 4.5:

4.3 Except as provided in Article 4.2, if the player having the move touches on the chessboard,with the intention of moving or capturing:

4.3.1 one or more of his own pieces, he must move the first piece touched that can be moved

4.3.2 one or more of his opponent’s pieces, he must capture the first piece touched that can be captured

4.3.3 one or more pieces of each colour, he must capture the first touched opponent’s piece with his first touched piece or, if this is illegal, move or capture the first piece touched that can be moved or captured. If it is unclear whether the player’s own piece or his opponent’s was touched first, the player’s own piece shall be considered to have been touched before his opponent’s.

4.5 If none of the pieces touched in accordance with Article 4.3 or Article 4.4 can be moved or captured, the player may make any legal move

Art 2.2 assigns ownership of the white pieces to White and the black pieces to Black at the start of the game and there are no rules of play that result in a change of ownership of any pieces. 

(Art. 4.5 says "any legal move" but art 4.3 is still in effect so a player can move only his own pieces even when this article comes into effect.)

Regarding the question of whether a flag fall when the king is in check is checkmate or not the answer would appear to depend on the exact interpretation of some articles.

Firstly the definition of checkmate:

1.4 The objective of each player is to place the opponent’s king ‘under attack’ in such a way that the opponent has no legal move.

1.4.1The player who achieves this goal is said to have ‘checkmated’ the opponent’s king and to have won the game.

This depends on the interpretation of the phrase "has no legal move". The meaning of "a player has the move" is defined in art. 1.3

1.3 A player is said to ‘have the move’ when his opponent’s move has been ‘made’

White isn't defined to have the move at the start of the game (though he must make the first move by art. 1.2) but his king is not in check, so it's not checkmate anyway. However arts. 4.3, 4.4 and 4.5 consequently don't apply either, so he may move a black piece. I think this is a mistake in FIDE's formulation.

The meaning of legal move is defined in art. 3.10.1. The meaning of "made" is defined (albeit incompletely) in 4.7-4.7.3.

I would therefore interpret checkmate to be a position in which a player has the move but cannot make any legal move (indeed cannot make any move, since licit moves are necessarily legal in the defined sense). You may disagree with this interpretation, in which case you should say what you think it means for a player to "have" a legal move. 

Secondly article 6.3.1

6.3.1 When using a chessclock, each player must complete a minimum number of moves or all moves in an allotted period of time including any additional amount of time with each move. ...

Note that the laws do not explicitly state that the game is immediately terminated when the flag falls. The game is naturally terminated because the player who's flag falls has violated art. 6.3.1 and the game has ceased to be a licit chess game. 

In that case art. 6.9 actually deals with an irregularity and should appear under article 7. 

6.9 Except where one of Articles 5.1.1, 5.1.2, 5.2.1, 5.2.2, 5.2.3 applies, if a player does not complete the prescribed number of moves in the allotted time, the game is lost by thatplayer. However, the game is drawn if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves.

In my view the second sentence here is always satisfied if 6.9 becomes relevant, so the game in that case is always a draw. Whether or not it's also lost by the player who's flag falls depends on the interpretation of the word "however". This would normally be taken to gainsay the preceding text, so it would not be lost on that basis. On the other hand if the offending player's king were also in check that would indeed satisfy my suggested interpretation of checkmate so he would lose under article 5.1.

I am aware, of course, that this would not normally correspond with the way an arbiter would score things, I'm just offering what I think is a correct reading of the FIDE laws.

@MARattigan:

Am I to understand from your reply to Numquam that you changed your mind about "the series of legal moves" to be one in which the legal moves need not alternate between the two colors? Or did I misunderstand your earlier comments? And if you did change your mind, did you also change your mind about the legal moves not needing to be playable?

About checkmate I'd say that a checkmate cannot be established until the move is finished. For instance while playing a move one might move a piece via a square where the opponent would be checkmated but unless the move is completed at that point it can't be counted as a checkmate. If the flag falls before checkmate move is completed, it's therefore not checkmate and you lose (unless there is a minimal draw). If the checkmate move was completed before the flag fell it's a win for the checkmate giver. This appears to be not as much an issue in the rules as in the observation of the event order which is a tricky thing.

Btw, both situations frequently happen during blitz tournaments and are arbitrated in this way - if my memory does not deceive me (it's a long time ago).