187. Sprenger=J 1/2-1/2

Problemist of Ukraine 2022 ℹ

[Event "Problemist of Ukraine"]
[Site "?"]
[Date "2022"]
[Round "?"]
[White "187. Sprenger=J"]
[Black "?"]
[Result "1/2-1/2"]
[SetUp "1"]
[FEN "5k2/8/1K2b1r1/1P2p3/1P6/8/3N4/6N1 w - - 0 1"]
[PlyCount "35"]
[EventDate "2022"]

{Themes: 11th WCCT theme - sacrifice in solution and try; reciprocal change of solution and try in the two main lines} 1. Ngf3 e4 $1 2. Ne5 (2. Nxe4 $4 Bd5+ $19 {/Bf5+}) (2. Nd4 $2 e3 3. N2f3 Bg4+ 4. Kc5 Ke7 $19 {Even without engine it is clear that Black can always reach the won endgame RB vs. NN. Probably he will also win faster.}) 2... Rh6 3. Nxe4 $1 {Otherwise Black plays e4-e3, winning like in the line 2. Nd4. Now Black has to decide how to fire from the battery:} Bf5+ $1 {Main B. Prevents the tactic 3. ...Bd5+ 4. Nf6!, but now the bishop does not control the square b7.} (3... Bd5+ {Main A. Here the bishop is in the range of the white king and so White can play} 4. Nf6 $1 {11th WCCT theme} ( {logical try} 4. Nd6 $2 Rxd6+ 5. Kc5 {no threat Kxd5} Ke7 $1 $19 (5... Rd8 $2 6. Nc6 $1 Rd7 7. Ne5 $10)) 4... Rxf6+ 5. Kc5 $1 {with the double threat Nd7+ and Kxd5, forcing the bishop to leave the long diagonal.} Be6 6. b6 Bc8 7. b7 {/Nd7+ followed by b6-b7 also works} Bxb7 8. Nd7+ Ke7 9. Nxf6 $10) 4. Nd6 $3 {11th WCCT theme. Only this sacrifice keeps the black king out of play.} ( { logical try} 4. Nf6 $2 Ke7 $1 {/or Kg7 with transposition} (4... Rxf6+ $2 5. Kc7 Rh6 6. Nc6 {transposes to the main line}) 5. Kc7 Kxf6 6. Nc6 Rh7+ 7. Kb8 Bd7 $1 8. Nd4 {position X with bKf6} Ke5 $1 9. b6 Kxd4 $19) ( {try} 4. Kc7 $2 Bxe4 {is hopeless for White: the bishop stands on the right diagonal and the rook is not threatened.} 5. Nc4 Rh7+ $1 $19) 4... Rxd6+ 5. Kc7 Rh6 (5... Rd5 6. b6 $1 Rxe5 7. b7 Re7+ 8. Kb6 $1 $10) 6. Nc6 $1 ( {try} 6. b6 Rh7+ $1 7. Kb8 Be4 8. Nc4 Rb7+ $1 9. Kc8 {eg} Ke7 $19) 6... Rh7+ 7. Kb8 Bd7 $1 (7... Be4 $6 8. Na5 $1 {allows White to reach his ideal piece configuration and transposes into the solution after} Ke7 9. b6 Kd6 10. b7) 8. Nd4 {position X with bKf8} Ke7 9. b6 Kd6 10. b7 Bh3 $1 {Preparing Bg2.} ( {After the straightforward} 10... Bc6 { Black liquidates the pawn, but White escapes into stalemate:} 11. Nxc6 Kxc6 12. b5+ $1 Kb6 13. Ka8 Rxb7 $10) 11. Nb3 $1 {The knight is finally heading for the ideal square a5.} Bg2 12. Na5 Be4 13. b5 (13. Ka7 $2 Bxb7 14. Nxb7+ Kc6 15. b5+ Kxb5 16. Kb8 Kc6 $1 17. Nd8+ Kd7 18. Nb7 Rh5 $19 {with a well-known theoretical win}) 13... Bd5 14. Ka7 Kc5 15. Ka6 Rh8 16. Nb3+ $1 {The bishop needs to be decoyed away from the long diagonal.} (16. Ka7 $2 Bxb7 $1 17. Kxb7 Kxb5 18. Nc6 Rh7+ $19) 16... Bxb3 17. Ka7 Rh7 18. Ka6 $1 1/2-1/2