Test position: look but don't touch (avoid move)

[bob]

Bob,
Where did you get your 8 box from? I can't find many suppliers here in the UK.

I built my quad myself but wouldn't feel too comfortable doing the same with an 8 core machine.

This is a Dell box. Dual cpu, quad-core. This is one node of our 70-node cluster we bought about 3 years ago.

Dual-cpu (chip) boxes are pretty common. These boxes (in our cluster) are actually pretty cheap as they are 1U rack-mount machines.

[Albert Silver]

This was an interesting position, and kudos to Stockfish for instantly seeing what was going on.

[d]3B4/5p2/4p3/p2kP3/P1pP2P1/r1P2P1p/2K4P/8 b - - 0 113

The move to avoid is 1...Rxa4?? after which 2.Kb2! locks it in forever, and the white bishop and pawns decide the game on their own.

Although it is clear Rxa4 is bad, I think it does not lose the game. The white king is also locked to its place and the bishop cannot help his pawns because g6 is a white-coloured square, and as soon as the f3 pawn moves the black king has a path through e4 to help out on the kingside.

Feel free to test it, but Rxa4 loses. To begin with, after Kb2, the king has to move to c6.

[Terry McCracken]

This was an interesting position, and kudos to Stockfish for instantly seeing what was going on.

[d]3B4/5p2/4p3/p2kP3/P1pP2P1/r1P2P1p/2K4P/8 b - - 0 113

The move to avoid is 1...Rxa4?? after which 2.Kb2! locks it in forever, and the white bishop and pawns decide the game on their own.

Although it is clear Rxa4 is bad, I think it does not lose the game. The white king is also locked to its place and the bishop cannot help his pawns because g6 is a white-coloured square, and as soon as the f3 pawn moves the black king has a path through e4 to help out on the kingside.

Feel free to test it, but Rxa4 loses. To begin with, after Kb2, the king has to move to c6.

This is why I like this position so much. It's pretty instructive imho. White's K-Side pawns can move up the board and the center pawns sac themselves while the Bishop is on f6 to force the f-pawn home all the while Black's Rook is pinned to a4.

[royb]

This was an interesting position, and kudos to Stockfish for instantly seeing what was going on.

[d]3B4/5p2/4p3/p2kP3/P1pP2P1/r1P2P1p/2K4P/8 b - - 0 113

The move to avoid is 1...Rxa4?? after which 2.Kb2! locks it in forever, and the white bishop and pawns decide the game on their own.

Although it is clear Rxa4 is bad, I think it does not lose the game. The white king is also locked to its place and the bishop cannot help his pawns because g6 is a white-coloured square, and as soon as the f3 pawn moves the black king has a path through e4 to help out on the kingside.

Feel free to test it, but Rxa4 loses. To begin with, after Kb2, the king has to move to c6.

I can't see how white can make progress while the black king is moving between c6 and d5. Will you give me a hint?

Only a brief analysis with Stockfish, but this is what I see:

113. ... Rxa4
114. Kb2 Kc6
115. Bg5 Kd5
116. Be7 Kc6
117. Bf6 Kd5
118. f4 Kc6
119. f5 Kd5
120. Be7 exf5
121. gxf5 Kc6
122. Bc5 Kd5
123. e6 fxe6
124. f6

and white wins easily...

There are of course other lines to test, but this one shows that f4 and the eventual passer on the K-side wins for White.