[Event "Pattern Juggling: Middlegame block and lune"] [Site "https://lichess.org/study/uZFAS28p/pcN87F9E"] [Result "*"] [Variant "Atomic"] [ECO "?"] [Opening "?"] [Annotator "https://lichess.org/@/Illion"] [FEN "r2k1r2/p4P1p/1p2p1p1/3p4/1PpP2PP/2P5/P7/2RK3R b - - 0 1"] [SetUp "1"] [UTCDate "2017.08.25"] [UTCTime "23:24:42"] [Source "https://lichess.org/study/uZFAS28p/pcN87F9E"] [Orientation "black"] { In a complex middlegame, it can sometimes be difficult to evaluate positions based on sheer calculation. This is where small positional ideas like the block and lune pawn microstructures can help find the right move. What is going on in this position? Material is even, with only rooks and pawns on the board, so open files will be critical. Black has one rook tied down to stopping the f7-pawn, and stands worse. White wants to open files in order to exchange both rooks (or just the f8-rook) and promote. Black wants to keep the position closed and draw. The pawn situations on the a-, b-, g- and h-files are still fluid for the moment. White is threatening to set up two lunes with b5 or g5. Black needs to recognise this as a threat and act quickly. } 1... h6! { 1...h6! sets up a block on the kingside. This keeps the g- and h-files firmly closed. It also prevents white's bigger threat of g5! and opening the kingside, either getting an open h-file or a passed pawn, both of which would quickly end the game. } { [%csl Gh6,Gg6] } (1... a6? 2. g5! { If black does nothing significant or makes a block on the wrong side, white makes a lune on the kingside with 2. g5!. Now black will suffer the kingside opening. } { [%csl Rf8,Gh4,Gg5,Gg6,Gh7][%cal Rh1h8,Rh8f8] } 2... Ra7 3. h5 Kc8 4. hxg6 Re7 5. g6 hxg6 6. Rh8 Rd7 7. Rxf8 Rxf7 8. Ke2 $18 { White wins this rook-for-pawn endgame. }) (1... e5? { This attempt to blow up the centre and get counterplay doesn't work. } 2. g5! { The lune. } { [%csl Gh4,Gg5,Gg6,Gh7] } 2... exd4 3. h5 Kc7 (3... Rc8 4. hxg6 d4 5. Rh6 Rc6 6. Rd6+ Rxd6 7. Ke2 Kc7 8. g6 hxg6 9. Rh1 d3+ 10. Kd2 Re8 11. fxe8=Q $18 { White wins this endgame. }) 4. hxg6 Rfe8 5. Rh6 Re6 6. f8=Q Rxf8 7. Rxe6 $18 { White wins this endgame. }) 2. b5 { White sets up the queenside lune, else black will play 2...a6 with another block then shuffling about for a draw. } { [%csl Gb5,Gb6,Ga7,Ga2] } 2... a5! { Black seals off the queenside, forcing an en passant capture. } 3. bxa6 (3. h5 g5 4. Re1 e5 5. dxe5 Ra7 6. Re5 Kc8 { White cannot make progress except by sacrificing a rook for a pawn, after having manoeuvred all pieces to their optimal locations. Even then black will be able to get at least one rook in to force a perpetual check. }) 3... Ra3! $10 { Black "mines" b1, and white cannot make progress. If at some point Rb1 is played, black has ...Rxa2 followed by ...Rxf7, and white has nothing better then perpetual check, down rook for two pawns. See the example continuations. } { [%csl Ga2,Gb1,Gf7][%cal Ga3a2,Gf8f7] } 4. Ke2 (4. h5 g5 5. Re1 e5 6. dxe5 b5 7. Re5 Kc7 { White has no entrance, the attacked pawns on f7 and a2 preventing white's rooks from using the squares they really want to. }) 4... Kc7 5. Rb1 Rxa2 6. Ra1 Rxf7 7. Ra7+ Kd8 { White should take the perpetual. Black will also be careful to keep the king close to the kingside pawns to avoid any passed pawn tricks with Rxg6 or Rxh6. } *