Most games have some way to make sure they cannot go on forever.
1) Chess: I had thought there was a 50-move rule and a 3-times-same-position rule, but its a byte more complicated than that, see here. There is also a chess clock. Suffice to say, Chess can never on forever (though it may seem like it does).
2) NIM: Eventually all of the stones are gone. There may be more complicated versions where you can add some stones, but in those versions I suspect that there is some parameter that goes to 0.
3) Basketball, Football, Hockey, Soccer: These all have a clock so they are time limited. For overtime there are also rules that make sure the game cannot go on forever. Or maybe its just very rare: what if the Superb Owl (spelled that way to avoid lawsuits, see here) is tied 0-0 at the end of the four quarters and goes into overtime and... nobody scores... ever. Could the game go on forever or would the referees declare it a tie? In the regular season there are ties, but in the in the superb owl? Actually this may be more a problem in the playoffs since you need to determine who goes to the next round.
4) Take your favorite game. I would bet dollars to doughnuts (what an odd phrase---see here for more about the phrase) that there is some mechanism to make sure the game ends. An exception that Darling pointed out to me: If in Gin Rummy both players are terrible then the game can go on forever. This is probably true for other games as well and actually makes the question into two questions (a) will a game terminate no matter what the players do, and (b) (not sure how to formalize) will a game terminate if both players are trying to win and are making reasonable moves.
You may have noticed that in item 3 I left out Baseball. There is no clock in baseball. So one way the game can go on forever is to have a tie and extra innings and nobody scores. I think the umpire has the authority to call it a tie. (Incidentally, the shortened baseball season has a new extra inning rule---each inning starts with a runner on second. See here,) When Lance read an earlier version of this post he pointed me to 5 ways a game can go on forever, not counting the example I have later in this post. Here is where Lance found the question and answer (look on the first page under Speed Department for the question, and the very end of the second page for the answer). I also did my own writuep with more details, see here. Also of interest (though not if you were actually at the game this happened), the record for number of times a player has a foul with 2 strikes is 16, see here.
However, I came across an example more obscure than any of those.
Here is what happened (and you can see the video of it here, though it really starts about a minute into it. Keep reading- it looks like its another post, but its part of this post:
Back in 2008, the Yankees drafted a pitcher named Pat Venditte. What made Venditte unusual is that he can throw with both hands. In other words, he’s a switch pitcher. When he was drafted, he was assigned to the Staten Island Yankees, a low A ball team.
In his first game (against the Mets farm team, the Brooklyn Cyclones), Venditte came in to pitch. After getting the first two batters out and giving up a single, he then faced Ralph Henriquez, was a switch hitter. What happened next resembled an Abbott and Costello comedy routine. Venditte would put the glove on one hand (he had a specially made glove that could be worn on either hand) and Henriquez would then step across the plate to bat from the other side. Venditte would then switch his glove hand again and Henriquez went back to the other side.
Eventually, after much discussion, the umpires ruled that Henriquez would have to choose a batting side first, before Venditte had to commit. Henriquez was mad and, after he struck out, he slammed the bat against the ground in frustration.
The umpires were, in essence, winging it, because there was no rule to cover the situation. Eventually, the higher ups in baseball did write a rule to cover the situation — the opposite of the umpires’ decision.
Soccer can go on indefinitely in penalty shoot-outs. The likelihood of going on for t minutes is exponentially small in t, but not zero.
ReplyDeleteThe former Dutch World Chess Champion and mathematician Max Euwe (1901-1981) proved in 1929, rediscovering the Prouhet–Thue–Morse sequence (using that it contains no cubes), that the rules of chess at that time did not preclude an infinite number of moves. See his "Mengentheoretische Betrachtungen über das Schachspiel". Proc. Konin. Akad. Wetenschappen. 32 (5). Amsterdam. pp. 633–642 (available online), and also https://www.chessprogramming.org/Max_Euwe.
ReplyDeleteIf you aren't allowed to add new players once the game has started, then all of these games are finite.
ReplyDeleteA fivefold repetition is an automatic draw under FIDE rules but some national chess federations (e.g., the USCF) don't make it an automatic draw, so technically the game can go on forever, since threefold repetition and the fifty-move rule don't trigger automatic draws either (the draw must be claimed by one of the players).
ReplyDelete