Page 1 of 2

The 75 move rule

Posted: Wed Mar 11, 2015 9:31 am
by sje
The 75 move rule was apparently instituted by FIDE in mid 2014. Has anyone incorporated it in their chess program?

From the Laws of Chess http://www.fide.com/fide/handbook.html? ... ew=article
9.6

If one or both of the following occur(s) then the game is drawn:

a. the same position has appeared, as in 9.2b, for at least five consecutive alternate moves by each player.
b. any consecutive series of 75 moves have been completed by each player without the movement of any pawn and without any capture. If the last move resulted in checkmate, that shall take precedence.

Re: The 75 move rule

Posted: Wed Mar 11, 2015 9:44 am
by Zenmastur
Wasn't it Bob who said this wouldn't happen again?

Regards,

Zen

Re: The 75 move rule

Posted: Wed Mar 11, 2015 9:58 am
by Evert
sje wrote:The 75 move rule was apparently instituted by FIDE in mid 2014. Has anyone incorporated it in their chess program?

From the Laws of Chess http://www.fide.com/fide/handbook.html? ... ew=article
9.6

If one or both of the following occur(s) then the game is drawn:

a. the same position has appeared, as in 9.2b, for at least five consecutive alternate moves by each player.
b. any consecutive series of 75 moves have been completed by each player without the movement of any pawn and without any capture. If the last move resulted in checkmate, that shall take precedence.
I don't think this changes things in practice: the rule kicks in if neither player claimed a draw under the 50-move or 3-fold repetition rules, but could have done so. If that happens, the game is basically decided for them at 75th move or after the 5th repetition.

I think all programs (and interfaces) claim the draw before then.

Re: The 75 move rule

Posted: Wed Mar 11, 2015 10:37 am
by Ferdy
sje wrote:The 75 move rule was apparently instituted by FIDE in mid 2014. Has anyone incorporated it in their chess program?

From the Laws of Chess http://www.fide.com/fide/handbook.html? ... ew=article
9.6

If one or both of the following occur(s) then the game is drawn:

a. the same position has appeared, as in 9.2b, for at least five consecutive alternate moves by each player.
b. any consecutive series of 75 moves have been completed by each player without the movement of any pawn and without any capture. If the last move resulted in checkmate, that shall take precedence.
I plan to implement it in next release.

Re: The 75 move rule

Posted: Wed Mar 11, 2015 5:32 pm
by bob
Zenmastur wrote:Wasn't it Bob who said this wouldn't happen again?

Regards,

Zen
This is not quite the same as the 50 move rule. Players can still claim a draw at move 50 as before. Apparently this is a TD rule that lets him end a game after 75 moves if neither player is willing to claim the 50-move draw.

In 1981, Cray Blitz won the Mississippi State Closed Championship tournament. In that event, there were two guys that disliked each other so much they got into some sort of a drawn endgame, but with queens still on the board, and they continued to play. All the other games had ended by 8pm, but they played until after 5am the next morning, requiring the TD to stay there, and they finally agreed to a draw.

I assume this rule is to avoid that.

Five-fold, too

Posted: Wed Mar 11, 2015 9:01 pm
by sje
It's not clear to me that the first part is a simple extension of the three-fold rule to a five-fold rule, although that may be the case.

My programs always claim a draw as soon as possible under the three-fold and fifty move rules. I guess that most others are the same. Only a referee program needs to be aware of the new rule.

----

As I've stated before, I'd toss the three-fold rule and replace it with a rule which forced an immediate draw result upon the very first time a position was repeated. This would simplify the game by removing a hack which some human players use to evade time controls.

Re: The 75 move rule

Posted: Wed Mar 11, 2015 9:02 pm
by syzygy
Zenmastur wrote:Wasn't it Bob who said this wouldn't happen again?
I have said it as well. Once FIDE decided that it made no sense to track "longest mate records" (or rather, DTZ records) discovered by computers, there is no reason anymore to change the 50-move rule for over-the-board play. In a way this new 75-move rule reinforces the 50-move rule.

Now let's see how long it takes before correspondence players get back in line :-)

Re: The 75 move rule

Posted: Thu Mar 12, 2015 6:10 am
by sje
bob wrote:Apparently this is a TD rule that lets him end a game after 75 moves if neither player is willing to claim the 50-move draw.
Almost. My reading is that the TD has no choice in the matter, and the game is drawn even if it's not played under direction.

You're right in your conclusion that it's a rule for encouraging tournament players to avoid inconsiderate jackass behavior inconveniencing the TD and all the other players.

I'd modify the rule for games where at least one player (a program) has access to tablebases AND is winning AND can show that progress towards a checkmate is being made with each move AND can produce moves nearly instantaneously AND can specify a maximum game length. Failure to mate would mean a forfeit -- a penalty to discourage false claims.

Re: The 75 move rule

Posted: Thu Mar 12, 2015 6:36 pm
by bob
sje wrote:
bob wrote:Apparently this is a TD rule that lets him end a game after 75 moves if neither player is willing to claim the 50-move draw.
Almost. My reading is that the TD has no choice in the matter, and the game is drawn even if it's not played under direction.

You're right in your conclusion that it's a rule for encouraging tournament players to avoid inconsiderate jackass behavior inconveniencing the TD and all the other players.

I'd modify the rule for games where at least one player (a program) has access to tablebases AND is winning AND can show that progress towards a checkmate is being made with each move AND can produce moves nearly instantaneously AND can specify a maximum game length. Failure to mate would mean a forfeit -- a penalty to discourage false claims.
I'd also bet this was done to help players in speed chess games. Now you don't have to stop and check your score sheet to see if it has really been 50 moves or not. When you hit 75 it is over and going beyond that in a time scramble has no harmful effect, the game is drawn at 75.

Re: The 75 move rule

Posted: Fri Mar 13, 2015 11:32 pm
by wgarvin
sje wrote:
bob wrote:Apparently this is a TD rule that lets him end a game after 75 moves if neither player is willing to claim the 50-move draw.
Almost. My reading is that the TD has no choice in the matter, and the game is drawn even if it's not played under direction.
Fortunately, it should have no effect on tablebase generation that includes support for the 50-move rule. Since after 50 moves either player could claim the draw at any time, this 75-move rule does not affect the GTV.