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Kevin Bonham
30-08-2009, 06:25 PM
2r3k1/2P5/6K1/8/8/8/7p/7R w - - 0 1

Martin-Simpson - Riley, Southern Tas Junior Champs today.

White won this position after 1.Rc1 Rxc7 2.Rxc7 h1=Q 3.Rc8#

But of course 1...h1=Q instead of recapturing would have drawn.

What is white's best winning attempt and how should black respond to it? With best play is this a win for white or a draw?

See if you can work it out without checking a tablebase or engine. It's quite a rewarding exercise.

Rincewind
30-08-2009, 06:53 PM
I'm not sure by what criteria you are measuring the "best try" but I suspect this position is drawn with best play unless Black is careless and allows himself to be mated.

Against 1.R-anywhere moves Black should play 1....h1=Q and after 2.Rxh1 Rxc7 we have a draw. But if White can set up a mate then maybe a swindle is possible and White can ignore the queen on h1. Thus the best try is (I think)

1.Rd1

Now
(A) if 1.... h1=Q then 2.Rd8+ with mate in 1, and
(B) if 1.... Rxc7 then 2.Rd8#
(C) if 1.... Rf8 then 2.... Rb1! puts Black in zugswang and wins.
(D) Blacks only reasonable move then is 1.... Kf8 and this is sufficient to remove the mating threat and thus draws. 2.Rd8 Ke7! 3.Rxc8 h1=Q draws

(A) and (B) are unlikely to get played very often but in time trouble you might occasionally swindle a game with an opponent playing (C).

Saragossa
30-08-2009, 07:07 PM
A) 1.Rd1 Rxc7 2. Rd8#
B) 1. Rd1 h1=Q 2. Rd8+ Rxd8 3. cxd8=R#
C) 1.Rd1 Rf8 (Not ...Re8 2.Rd8!) 2.Rb1! h1=Q(2...Rc8 3.Rb8 and mate follows) 3.Rxh8 Rf7 4. Rc1 and after a few checks black runs out and white queens and after 3...Rc8 4. Rd8 or Rb8 wins.

Ok from Rincewinds post. 1...Kf8 2. Kf6 (if 2...Kg8 3.Rd8+ Kh7 4.Rxc8 h1=Q 5.Rh8+ and mate is forced) 2....Ke8 I can't find anything.

Ian CCC
30-08-2009, 07:53 PM
If any K move, then Rxc7 draw. If any R move other than Rd1, then h1=Q Rxh1 Rxc7 draw. So, 1.Rd1 seems white's best try, however Kf8 seems to stop progress. If 2.Rd8+ Ke7 3.Rxc8 h1=Q draw. If 2.Kf6 Ke8 draw.

Kevin Bonham
30-08-2009, 09:30 PM
All the above posters are correct and doing better than we did.

Our (mainly my) attempts went something like this:

OK, so 1.Rd1 is a winning try.

But black has ...Rf8 when 2.Rd8 allows h1=Q and now 3.Rxf8 doesn't work because the king escapes.

Ah, but white has 2.Rb1 zugzwang! (I think this zugzwang is especially neat).

Then sometime later I saw 1...Kf8! Pretty soon we found 2.Kf6 Ke8 and then there really is nothing. Except that someone suggested 3.Ke6 forced Kf8, which it doesn't, of course, since there is no longer a back rank mate so black now takes the pawn

By the way the previous moves to reach this position were 0. R(c1)-h1 R(f8)-c8. White should have queened with an easy win instead of playing Rh1, while Black's reply was correct.