Matemax wrote on 08/26/08 at 13:22:44:


Thanks - that's a really useful site!

I've just played around with it a little and found that White can actually win if his rear pawn is on c2 instead of c3!   

At first just the thought of this made my head spin, then I realized that it is because this time when White plays his king to c4 and Black goes Kc6, then White has c2-c3, forcing the black king to give ground. The white king can reach b5 without Black being able to counterattack as in the original puzzle. 

White either wins the b-pawn or forces through c5-c6 bxc6 Kxc6, reaching a basic winning position: 
1 Kd2 Kc7 2 Kc3 Kd7 3 Kc4 Kc6 (drawn if the pawn is already on c3) 4 c3! Kd7 5 Kb5 and wins.

No wonder these are difficult when their solution is wrong. I just checked and it's supposed to be a win for white but the tablebase says otherwise. This is not the first time that the book has had the wrong solution to a puzzle, did they not have tablebases in 1998 do you think or is the author just lazzy?

Ugh, I missed the ...Ke6 or ...Ke5 idea. 

Does anyone have a tablebase? Maybe someone can check.

sssthepro wrote on 08/25/08 at 12:43:49:


That’s the plan, but I think this one should be a draw. It's very tricky though, since it's all down to king moves. Some considerations:

1) If the b7 and c5 pawn are exchanged, White wins if can get his king to c6 (with or without the opposition), or c5 with the opposition, assuming he is not losing his rear c-pawn.

2) If White plays c3-c4 too early he might not be able to gain the opposition later, lacking a tempo move.

3) If the White king goes to d5, Black draws with no problems as long as he can answer Kd5 with …Kc7 or …Kd7.

4) The plan of sending the white king to b5 is far more dangerous, since the b7 pawn hinders Black’s king manoeuvres.

5) Answering Kc4 with Kc6 is OK, but Black must NOT play …Kc6 if White can answer Kc4, which means that Black cannot really prevent Kb5.

6) If the White king reaches b5 with the Black king on c7 or d7, White wins, since the black king must give up more ground to protect the b-pawn and then White is able to play c6, bxc6 Kxc6 with a standard win; so passive play by Black loses.

7) Black must therefore be able to answer Kb6 with a move that attacks the front c-pawn, which means that the black king must be prepared to abandon the b-pawn and deploy actively in counter-attacking against the white pawns.

Ok, let’s try to express this in moves:

1.Kc2 Kc7 2.Kb3 Kd7! - only move- 
[not 2...Kc6? 3.Kc4 Kc7 4.Kb5 Kd7 5.Kb6 Kc8 6.c6 bxc6 7.Kxc6+-] 
3 Kb4 [3.Kc4 Kc6=] 3…Ke6! o.m. and now:
a) 4.Kc4 Ke5! o.m. 5.Kb5 (5.c6 bxc6 6.Kc5 Ke4!= o.m.) 5...Kd5 6.Kb6 (6.c4+ Kd4) 6...Kc4=; 
b) 4.c4 Kd7 o.m. 5.Kb5 Kc7 o.m. 6.Ka5 Kc6 7.Kb4 b6=; 
c) 4.Kb5 Kd5 o.m. 5.c4+ [5.Kb6 Kc4= o.m.] 5...Kd4= 
d) 4.Ka5 Kd5 5.Kb5 Ke4! o.m. 6.Kb6 Kd5 7.c4+ Kd4=

So little material, yet so tricky. Please point out any mistakes or any important ideas I might have missed.

“Thou shalt not trade down to K+P unless you can safely bet your first-born child on the result.” (Soltis)

Even though I feel like things are progressing now and I'm getting more solutions correct because of what I have learnt recently some "elementary" positions are still very difficult for me.

Here is one for example which I'm not quite sure about how to go about solving

White to move and win

Bocajaka wrote on 08/15/08 at 18:04:11:


I've not seen this before but it seems to me that this one has very little to do with getting the correct first move and, as with the other two examples I commented on, everything to do with thinking about basic positions. What position does White want to reach? Can he reach it, and if so how? 

Also, if intuition is the sum of what I have learned from experience, I should listen to the voice that tells me that since the action will be confined to the edge of the board, stalemate ideas might come in somewhere.

Well, ideally White would like to reach either the drawn position with just a black h-pawn left or the one with Black left with just a g-pawn no further forward than g5 and unable to take the opposition. So let's see what happens when both kings rush across towards the pawns:

1.Kb2 Kb5 2.Kc3 Kc5 3.Kd3 Kd5 4.Ke3 Ke5 5.Kf3 Kf5 6.Kg3 Kxg5 7.Kh3 
OK, White has lost a pawn, but his king is well placed for defence, and all he needs now is to exchange his g-pawn. Let's looks at the possibilities:
7...h4 allows 8 g3=, so Black has to move his king.
7... Kf6 or Kh6 allow 8 g4=
7...Kf4 8 Kh4 Kf5 9 g3 and any move of the black king allows g4=
7...Kf5 8 Kh4 Kf4 looks like the key line, apparently preventing g4 but then 9 g4! hxg4 is stalemate!
I'd like to say "Voila!" but perhaps I've missed something, since I’ve not reached Position 2.  Let me know please, since I'm definitely not a master.

Here is a quite interesting pawn endgame for everyone to solve if they wish:



Hint: to understand this position I experimented with just a lone king against three pawns, basically meaning that the other king is stalemated (see diagram below). I found that the king either stops the pawns or gets stalemated on the first rank.