Please allow me to reintroduce the perpetual check topic. I am currently discussing perpetual check with a player from another site. Please read below and comment, thanks!

My colleague wrote: “It occurs to me that as often as not, black will be wanting to force a draw to prevent the king from winning, so rewarding only black for such behaviour seems unjust.”

My reply: Black cannot force a draw in playing to the edge. If he is able to secure a perimeter, he will capture the king eventually. A draw by black only applies to corner tafl. Black can force a draw in corner tafl by securing the three squares that block each corner. Black could secure the corners too by making a complete ring of men around the board (see my game against the computer), but there is only a slim chance for a draw in the situation of a complete ring. The reason is because the second example has more men available to surround the king (the first example, the men cannot leave the corner squares to help, but in the second example black’s pieces can start moving inward one man at a time). It is more likely to be a black win. In any case, white has 0% chance of winning in either example.

Again, in edge tafl, black cannot force a draw. With so many open squares to protect, black cannot place three men at each corner. And if he can form a ring of men around the board (very rare), it always results in a white loss (white’s men will always end up captured one by one, including the king).

He continued: “If a stalemate occurs, it is both because white has not played well enough to escape, and that black has not played well enough to completely contain the king.”

I disagree. Perpetual check is not a stalemate, and the reason it is a loss for white is because white is the only player who controls check. Black can only react to check. Even if black plays perfectly, white can usually get a check in to the side. In edge tafl, even if black plays perfectly, there are circumstances where white can force a perpetual check in just a few opening moves.

Further, you stated “white has not played well enough to escape”. That is why he should not be able to force a draw. White would therefore only have to play hard enough or just good enough to force perpetual check, not win the game. Saying, “black has not played well enough to completely contain the king” is not fair. That now means that black’s goal has now changed to where he must not only capture the king, but now he cannot even allow a check for fear of perpetual check. Both burdens are not equal. You have put more burden on black.

He continued: “Neither side has played well enough, so there is nothing unfair about calling it a draw.“

Yes there is when only one player (white) controls check. Black can only get out of it once he is placed in it. Black’s goal should be to capture the king, period. Not to capture the king before getting into check or perpetual check. That is asking too much of black. Perhaps the best way to put it is this: Getting into perpetual check (white’s moves) is easier than preventing it (black’s moves). They are not the same as you are suggesting.

"We have adopted a system where a win is 1 point, and a draw is zero points for both players.Making it less tempting to force a draw, whereas .5 points for a draw makes it more tempting. Also, as a chess player, I'm sure you are aware of the leverage potential of threatening a player with a forced draw. This is something which we have discovered enriches hnefatafl enormously, and makes for some very entertaining end games."

I did not comment further.

SoM