Talk:Perpetual check

Example cut: not necessarily perpetual check

I cut this example from the article:

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Black to move can draw by perpetual check

In the second position, Black draws by giving perpetual check:

1... Qa1+!

2. Kd3 Qd1+

3. Ke3 Qg1+!

4. Ke4 Qg4+

5. Kd5 Qd7+

6. Kc5 Qa7+

7. Kc4 Qa4+

8. Kc3 Qa1+, etc.

By checking on the marked squares (including a4), White has no chance to stop the checks (Speelman 1981:34–35).

This is a draw but not necessarily a draw by perpetual check; white can avoid the checks and still draw the game by a sequence like this:

1... Qa1+

2. Kc2 Qxd4

3. g8=Q

You can confirm this by entering the original position (8/6P1/8/8/q2Q4/2K5/8/7k b - - 0 0) to the Nalimov Tablebase server. Gdr 19:47, 26 September 2008 (UTC)

Yea, well... White either has to give in to a perpetual check or give away his queen, and obviously he doesn't want to do that. Remember it is Black that is trying to draw, not White. Bubba73 (talk), 05:07, 27 September 2008 (UTC)

Is this a normal meaning of "perpetual check"? That is, it doesn't mean "inescapable sequence of checks" but "sequence of checks that can only be escaped with disadvantage?" If this is the case, then the example could be restored to the article with an explanation and a reference to a chess writer who uses the phrase with this meaning. Gdr 11:39, 27 September 2008 (UTC)

I'll look up some precise definitions later and see, But here White can escape the perpetual check by giving up his queen. But since White wants to play for a win, he obviously doesn't want to do that. Bubba73 (talk), 16:20, 27 September 2008 (UTC)

The Oxford Companion to Chess simply says "an unstoppable series of checks usually instigated to avoid loss of the game", which doesn't clear it up. Golombek's Encyclopedia isn't any more helpful. But I think it is implied that if he has to give up his advantage (or even get checkmated) to get out of the perpetual check, it is still basically perpetual check. Bubba73 (talk), 02:20, 29 September 2008 (UTC)

The only way White can escape the checks is by hanging his queen, resulting in a dead-drawn Q v. Q ending after Black takes White's queen and White promotes her pawn to a new queen. I think under those circumstances it's reasonable to describe the position as one where Black draws because of perpetual check. Krakatoa (talk) 03:58, 29 September 2008 (UTC)

Yes, in this case I think it is safe to say that the perpetual check forces a draw, one way or the other. I don't think Black can draw without it. Bubba73 (talk), 04:55, 29 September 2008 (UTC)

No-one doubts, I think, that this position has perpetual-check-like features. I have three questions: (1) Can we verify that chess writers use the term "perpetual check" to include positions like this? In particular, what does Speelman say in the cited work? (2) How common is it for chess writers to use the term broadly? Is it a majority or minority position? Can we find examples other than Speelman? (3) Even if we can find several chess writers who use the term broadly, is it a good idea for pedagogical reasons to place this example second in the article? Might it not be better towards the end, with an introduction along the lines of "some chess writers, e.g. X and Y, define the term more broadly, including positions where a sequence of checks can be escaped, but the escape leads to disadvantage for the escaping player." Gdr 12:51, 29 September 2008 (UTC)

For #1, Speelman has a section "Perpetucal check and perpetual attack". He says "In a sense perpetual check is only one example of perpetual attack - any manoeuvre whereby the weaker side forces the stronger side to repeat a position. First some examples of perpetual check." Then he gives that position, with the caption "example of perpetual check". Then he continues "Perpetual check, or the threat of it, is one of the defender's main resources in queen and pawn endgames. In diagram 60 Black can give perpetual check immediately..." and he gives moves. "By checking on the squares which mark out the perimeter of a square Black gives White no chance to vary." He says nothing about giving up the white queen to end the perpetual check. But even if White does this, Black can either have a perpetual check or force the exchange of queens. Chess writers make some assumptions about what the reader will understand. Bubba73 (talk), 15:10, 29 September 2008 (UTC)

What if we change it to "White cannot stop this series of checks except by giving up his queen." Bubba73 (talk), 15:16, 29 September 2008 (UTC)

Yes, that sounds like a good way to phrase it. Gdr 15:28, 29 September 2008 (UTC)

Perpetual pursuit

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Perpetual pursuit

We should probably give an example of perpetual attack / perpetual pursuit that is not check, come to think of it. A nice study is this one by S. Birnov (1928) given in Seirawan's Winning Chess Tactics). 1.a6 Bxc4 2.e4+! (restricting the bishop to half the diagonal) 2...Kxe4 3.a7 Bd5 4.c4 Ba8 5.Kb8 Bc6 6.Kc7 Ba8 and the perpetual pursuit is achieved. (An immediate 1.e4+? fails to 1...Ke5! 2.a6 Bh7 3.a7 Bxe4 and the pawn is stopped.) Double sharp (talk) 08:56, 2 October 2021 (UTC)

(Bilek vs Schussler 1978 is a real-game example.) Double sharp (talk) 12:25, 2 October 2021 (UTC)

I think that is OK. It probably needs a little explanation of what will happen from there in the 1978 game. Bubba73 ^{You talkin' to me?} 16:26, 2 October 2021 (UTC)

I added it. Strangely Seirawan and Silman don't attribute the Bilek vs Schussler game, so I should probably find a source for that. Double sharp (talk) 08:53, 5 October 2021 (UTC)

@Double sharp: Regarding this, I don't understand why black has to play 2... Kxe4? Can't they just play something else and avoid the perpetual pursuit? Vanjagenije (talk) 22:11, 24 November 2024 (UTC)

@Vanjagenije: Because otherwise the Black bishop cannot make it in time to stop the pawn, as d5 is denied to it by the e4-pawn. Double sharp (talk) 02:37, 26 November 2024 (UTC)

Yes, I see. You are correct. Vanjagenije (talk) 08:47, 26 November 2024 (UTC)

Chekhover and Korolkov, Chigorin Memorial, 1949–1950

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Reciprocal pursuit

P.S. Also possible is reciprocal pursuit when both sides have nothing better than to chase each other. See the study to the right. I'd like to add it (probably without the lead-in), if I can find an actual sourced annotation for what's going on. Mainline from Roycroft's The Chess Endgame Study: A Comprehensive Introduction (it's #375 there): 1.f7 Bd6+ 2.Kb2 Nh6 3.f8=Q+ Bxf8 4.Nxf8 Rf4 5.Ng4 Nxg4 and the pursuit starts: 6.Ne6 Re4 (6...Rf6 7.Nc7+ Kb7 8.Nd5 and 9.hxg4) 7.Ng5 (7.Nc5? Rxc4 8.Nd7 Rd4 9.Nb6+ Kb7 10.Kc3 Rd8 11.Nc4 Nh6; 7.Nc7+? Kb8 8.Na6+ Ka7 9.Nc5 Rxc4 and wins) 7...Re5 8.Nf3 Rf5 9.Nd4 Rf4 10.Ne6 Re4 11.Ng5 and drawn. Double sharp (talk) 09:04, 5 October 2021 (UTC)

Larry Kaufman's Kaufman's New Repertoire for Black and White uses "perpetual 'check' to the queen" to refer to such a perpetual pursuit in his opening analysis of the Marshall: 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 0-0 8.c3 d5 9.exd5 Nxd5 10.Nxe5 Nxe5 11.Rxe5 c6 12.d4 Bd6 13.Re1 Qh4 14.g3 Qh3 15.Qf3 Bg4 16.Qg2 Qh5 17.Be3 Rae8 18.Nd2 Re7 19.a4 Rfe8 20.axb5 axb5 21.Bxd5 cxd5 22.Qf1 f5 23.f3 Bh3 24.Qxb5 f4 25.Bf2 fxg3 26.hxg3 Bd7 27.Qf1 Bh3 28.Qd3 Bf5 and there is nothing better than to repeat. Double sharp (talk) 23:22, 29 April 2023 (UTC)