More on perpetual checks.
Adam wrote:And with the addition that any repeat move that involves a checking move may not be repeated more than 3 times, at which point the checking player must make a different move.
Hagbard wrote:In all these cases, one of the parties ("the attacking party") is trying to accomplish something which turns out not to be possible, because the opponent is able to prevent it. So the "attacker" must accept that his attack cannot succeed and must stop his perpetual moves.
A rule to solve all these cases could be, as suggested by conanlibrarian and Adam:
Rule+3) If a series of moves is repeated three times, the offensive player (i.e. the one performing a threat) must find an alternative move. If no offensive player can be determined, the game is a draw. [in Cartier's and conanlibrarian's words]
MaC wrote:I learned 20 years ago, the king have to escape otherwise he is starving to death during the rampart.
crust wrote:The only problem I can think of is if the two players don't agree which one of them is the "offensive" player. I suppose in that case they would have to agree on a draw anyway, but then we're back where we started with draw-by-repetition. In cases where check is involved, the offensive player is easy to identify, so possibly this rule should apply to perpetual check only. That still leaves us with the possibility of draw-by-repetition where check is not involved, but if check is not involved, neither player is compelled as strongly to repeat the moves, and each one can make his own value judgement of whether they offer or accept a draw, or make an alternative move.
I can (just) imagine a scenario where both players are checking each other on consecutive repeating moves, but the chances of it arising in a game are infinitesimal. Even so, the following formulation would force whichever player had started the checks to break the cycle:
Alternative statement of rule #3: Neither player may make the same checking move three times in a row.
crust wrote:Each player is creating check every other move. Which one is the "offensive" one?
Adam wrote:And if mate in two doesn't count as check, then here white can force black to lose, by making black put white into perpetual check. At which point the universe implodes.
The discussion reveals that the perpetual check is a complicated matter, and crust and Adam found very inventive borderline cases!
As mentioned, perpetual check is a draw in chess.
As also mentioned in the discussion, perpetual moves can occur in many ways:
- direct check from white or black or both
- indirect check in two, three, four etc. moves
- one party trying to capture an enemy piece
- or whatever other reason
A rule could require that "the attacker" breaks the deadlock, but it has been pointed out that it's not always simple to determine, who exactly is the "attacker". What if fx. white wants to move a piece strategically closer to a corner and black blocks because it's a very dangerous move. Nothing particularly is "attacked", so if the two parties do perpetual moves as a result, is it a draw then? If so, white achieves either a draw or else a move highly unfavourable to black, all at the expense of black.
The simplest rule would be to still let all perpetual moves be a draw (or to convert all perpetual move draws into black wins).
Another solution could be a generalized rule which integrates most of the proposals from this discussion.
Any perpetual moves
situation can be viewed to start this way:
1. one party (called the "attacker") moves some piece to some square
2. the opponent (called the "defender") does a blocking move for whatever reason
3. the "attacker" side steps to keep up the attack
4. the "defender" also side steps to keep up the blocking
3. and 4. is repeated indefinitely
Adam's example shows that the side stepping may also include a full row and not only two squares.
The generalized rule could be
, that in all cases
the party who did the move in point 1
must do no more than 4 side steps, after which he
must break the deadlock (i.e. when the point 1 position is repeated 3rd time). Even when using squares from a full row the way it's done in Adam's example, it's counted as side steppings.
- The game retarding situation shown in an earlier note
http://aagenielsen.dk/hnefataflforum/ph ... p=332#p316
is very rare. The perpetual checking king is protected to one side by a barrier of whites and can take breaks in the side stepping. Normally the stepping party must continue the "attack" or the whole situation will alter. Anyway, with a perpetual move rule the position in the example is to no advantage for white.
- I can imagine that such a rule could've been in function even in the Iron- and Viking Ages. Not so formally expressed, but the players would intuitively know, who is the "attacker" and who must break the lock. And if they couldn't reach an agreement on the matter, they'd finish the game in a direct, physical fight instead.
- Regarding the idea of converting all perpetual move draws into black wins:
What if white managed to occupy a corner, then black tries to take it back, and white must side step to keep the corner. It wouldn't be fair to turn white's proper defense of the corner into a black win and thus force white to do some other move and let black in.