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Sep0618   JohnBoy: <onedog>, <Yuridmi>  I too missed 21.Qxa8 Rxf4+ 22.Ke1 Qe3+ 23.Kd1 Rd4+ 24.Kc2 Rd8 25.fxe7 Bf5# as pointed out by <Glattke>. Too focused on 22...Qf2+ and missed the effect of 22...Qe3+ instead. 

Sep0618   saturn2: I was thinking after 21 Qb6 22 Re1 is also an answer to consider.
21...Qb6 22. Re1 Bb7 23. Qe3 

Sep0618   cormier: click for larger viewAnalysis by Houdini 4: d 22 dpa
<<<<<1. = (0.00): 18.Kf2> Rxd4> 19.a3> Rxd1> 20.axb4> Rd4 21.Ke3 Rxb4 22.Bd5 Rb8 23.Rxa7 Bf8 24.Nf6+ Kg7 25.Ne8+ Kg8 26.Nf6+ Kg7 2. = / + (0.40): 18.Nd6 exd6 19.a3 Qa5 20.Qe1 Qa6 21.Rc1 dxe5 22.Bxe5 Bxe5 23.Qxe5 b4+ 24.Kg1 bxa3 25.Qe7 Rd7 26.Qe8+ Kg7 27.bxa3 Qf6 28.Qe5 Qxe5 29.fxe5 Re7 30.Rc5 Rb8 31.Ba4 Be6 32.Kh2 Rb2 33.Re1 Rd2 34.Bb5 Bd5 35.Bf1 Rb7 36.Rec1 Rb3 

Sep0618
  agb2002: White threatens Qxa8 and fxe7.
The position of the white king invites to play 21... Qb6: A) 22.Qxa8 Rxf4+
A.1) 23.Ke1 Qe3+ 24.Kd1 Qxb3+
A.1.a) 25.Kc1 Rc4+ 26.Kb1 (26.Kd2 Rc2+ and mate in two) 26... Rc2 27.Ra2 Kh7 28.Re1 (28.fxe7 Be6 wins) 28... Bf5 29.Ka1 (29.g4 Rc1+ 30.Kxc1 Qc2#) 29... Qe3 30.Rb1 (30.Rxe3 Rc1#) 30... Rc1 wins. A.1.b) 25.Kd2 Rf2+ and mate in two.
A.1.c) 25.Ke1 Qe3+ 26.Kd1 Rd4+ 27.Kc2 Qd3+ 28.Kc1 Rc4#. A.1.d) 25.Ke2 Qxb2+ and Black seems to be able to force mate soon. For example, 26.Kd3 Qd4+ 27.Kc2 Rf2+ and mate next. A.2) 23.Ke2 Rf2+ 24.Kd3 (24.Ke1 Qe3+ 25.Kd1 Qd2#; 24.Kd1 Qd4+ and mate in two) 24... Qd6+ A.2.a) 25.Qd5 Qg3+
A.2.a.i) 26.Kd4 Rf4+ 27.Qe4 (27.Kc5 Qe3+ and mate soon) 27... Rxe4+ 28.Kxe4 Bb7+ 29.Kd4 e5+ 30.Kc5 Qxb3 wins decisive material. A.2.a.ii) 26.Ke4 Rf4+ 27.Ke5 Rc4#.
A.2.a.iii) 26.Qf3 Rxf3+ 27.gxf3 Qxf3+ seems to win decisive material. For example, 28.Kd2 Qxb3 29.fxe7 Qd5+ and the epawn falls immediately. A.2.b) 25.Bd5 Kh7 (threatens Bf5+ and Be6)
A.2.b.i) 26.Qxc8 Qxd5+ and mate in three.
A.2.b.ii) 26.g4 Qg3+ looks similar to A.2.a.
A.2.c) 25.Kc3 Qd2#.
A.2.d) 25.Ke3 Qf4+ 26.Kd3 Rd2+ 27.Kc3 Qd4#.
A.2.e) 25.Ke4 Rf4+ 26.Ke3 Qd4+ 27.Ke2 Rf2+ 28.Ke1 Qd2#. B) 22.fxe7 Bb7
B.1) 23.Qe3 Re8 (23... Rd1+ 24.Rxd1 Qxe3 25.Rd8+) followed by Qd6 touching f4 and e7 looks good for Black because the rook on h1 does not play yet. B.2) 23.Qg3 Qd6 with the same idea as in B.1. 

Sep0718
  patzer2: I missed finding yesterday's Thursday puzzle
solution 21...Qb6! + (2.49 @ 39 ply, Stockfish 9). However, I found studying the combination and what I missed very instructive. The most obvious threat posed by 21...Qb6! is the offer of Black's Rook on a8 as a poisoned piece. The Rook is poison because 22. Qxa8? allows Black to win the White Queen after 22...Rxf4+ 23. Qf3 (White's best reply in a lost position) 23...Rxf3+ + (7.67 @ 35 ply, Stockfish 9). If, after 22. Qxa8? Rxf4+ +, White moves the King, then it's matein15 with 23. Ke2 Rf2+ 24. Kd3 Qd6+ + or matein14 with 23. Ke1 Qe3+ 24. Qxb3+ +. The most difficult problem posed for White by 21...Qb6! is the decisive threat of a discovered attack with check after the best play moves 22. Re1 b4! 23. Kg1 Rxf4+ 24. Qe3 Qxf6 + (2.39 @ 30 ply, Stockfish 9), when Black's two extra pawns should prove decisive. P.S.: White's game takes a big turn for the worse after 18. Qf3? Rxd4 ∓ (1.30 @ 31 ply, Stockfish 9). Instead, 18. Kf2 Rxd4 19. a3 = (0.00 @ 33 ply) would have held the position level. 

Mar2322   Brenin: A repeat POTD, a Little too recent. Black can sacrifice his R on a8 with 21 ... Qb6 (denying the White K an escape via g1) since 22 Qxa8 now loses to 21 ... Rxf4+ (see 2018 kibitzing). If White wisely declines the R, e.g. with 22 Re1, then 22 ... Bb7 adds to his woes. 

Mar2322
  Knighthawkmiller: 1) =0.00 (23 ply) 21.Qxa8 Rxf4+ 22.Ke2 Rf2+ 23.Kxf2 Qd2+ 24.Kf1 Qd3+ 25.Kf2 Qd2+ missed opportunity for equality by Jeffrey X. 

Mar2322
  raymondhow: Tough Wednesday, only half credit for me. Found the first two moves, then wanted to play 23...Qxf6 for only small advantage compared to 23...g5. 

Mar2322   mel gibson: Very difficult  I still didn't get it after doing this puzzle before. See above. Stockfish 14.1 avx2 says:
21... Qb6
(21. .. Qb6 (♕a5b6 ♖a1e1 b5b4 ♖e1xe7 ♗c8a6+ ♔f1e1
♖a8f8 ♗b3xf7+ ♖f8xf7 ♕f3a8+ ♖d4d8 ♖e7e8+ ♖f7f8 ♕a8xd8 ♕b6xd8 ♖e8xd8
♖f8xd8 a3xb4 ♖d8d4 f4f5 g6xf5 g2g4 ♔g8f7 g4xf5 ♗a6d3 ♔e1f2 ♗d3xf5
b4b5 ♖d4d7 ♖h1c1 ♖d7b7 b5b6 a7xb6 ♖c1c6 ♗f5xh3 ♔f2g3 ♗h3d7 ♖c6d6
♗d7e6 ♔g3h4 ♔f7xf6 ♔h4h5 b6b5 ♔h5xh6 ♔f6e5 ♖d6c6 ♗e6f5 ♔h6g5
♖b7g7+ ♔g5h5) +5.87/41 199)
score for Black +5.87 depth 41. 

Mar2322
  An Englishman: Good Evening: Thought this looked familiar; commented on the game back on 6 April 2017. 

Mar2322   newzild: What <newzild> said in 2018. 

Mar2322   saturn2: Now I remember that I struggled with in the same way last time. 21...Qb6 is not the first I considered.
Only after Qc7, Qd2, Rxf4 Bb7 proved useless. 

Mar2322
  Teyss: Complex Wednesday. As per <agb2002> vintage 2018, it's more weekend level. I let SF run for one hour and White's best shot after 21...Qb6 is 21.Re1 b4!? 22.Kg1!?! (which human would play that?) Rxf4+ 23.Qe3 Qxf6 (4.11 at 49 ply). After 22.Qxa8+ the eval is 11.0 at 49 ply with the main line 22...Rxf4+ 23.Qf3 Rxf3+ 24.gxf3 Qxf6.
If 23.Ke2 instead of Qf3 it's mate in 16 after 23...Rf2+ but not Qf2+ which only gives Black a small edge. If 23.Ke1 it's mate in 14 after 23...Qe3+. All lines are very complex and the first two don't result in an immediate win. 

Mar2322
  scormus: <Teyss, Mel, ....> pleased to see I'm not the only one to find this tough.
The only move I thought it could be was ... Qb6, but didn't see a clear cut win after 22 Qxa8 Qxf4+ 23 Ke2, thinking ... Qf2+ was most likely. iSeems it wasn't!
But 23 Qf3 looked as if it would come out in B's favour after a bit of play. To be honest, I thought I must have missed something 

Mar2322   parch: 21...Qb6 ticks the box, 22.fe7
(22.Q:a8 R:f4+ 23.Ke1 Qe3+ and mate in 3 )
22...Bb7 23.Qf2 Re8 24.Re1 Qd6 25.Kg1 Rd2
26.Re2 R:e2 27.Q:e2 R:e7 with advantage. 

Mar2322   TheaN: This took me way too long, but eventually saw the concept. I saw so contemplating White's escape to g1 that I'm kind of surprised I didn't spot the immediate Qb6 sooner. The other options fail, simply because Black will lack firepower to keep the king contained. There's no DSB and the queen can only cover so many diagonals. <21....Qb6!> repositioning pieces and preparing Bb7. If 22.Qxa8, 22....Rf4+ 23.Qf3 Rxf3+ 24.gxf3 Qxf6 + and Black has a much better endgame. Mind that 23.Ke2 is <not> an easy variation: 23....Rf2+ 24.Kd3 (else mate) Qd6+! 25.Bd5 (Qd5 Bf5+) Kh7! +
click for larger view
Pretty silent move, it frees up the bishop, winning the game. If White declines <22.Re1> seems to be the best try and I underestimated this a bit. Black's much better, but requires to spot <22....b4! +>. If instead 22....Bb7?! 23.Bxf7+! Kh8 (Kxf7 24.Re7+ =) 24.Qe3 Qxf6 25.f5! ∓ Black will have to play accurately to keep advantage. 

Mar2322
  chrisowen: Nub grief auldy Qb6 goo it v amalgamate v it v aquakong it nub grief auldy had dt v it v i ms v it sequins q leg bring it v it wick z it vey pj ox cuff v it v ufo c it a hod gist v it c vol he mercy lop nick quick bow it v i z it v jo sax co it v i o bluffer buffy gold get v it v i fiddle iota had hog ago v it v i jug a doe it see its v c i i douche v it v i glad ho do oi v it v ho had boa tab jz it v i edit v i bluff it zilch affable pain it v cuff v it v dib gack gi fob bug farm climb bah cervix it v i c lav it block bade it v fag his v it v i bed it c dane x eg hail bon c v it v dex i daffy v it v fee it vet jog be it fc feed it edgy it a cox eg dex a v it v fane it v glad hire it v bad c it a sac v bade it v o golf oba ok fab brock out no court free it v i jif go x it i v any lex dr sane it a vol bah jaff v it er ye v it nog i v it v x nel red x oval bash it v it jeer fog fin i x y rex dane it v la lab sha vito shaolin it v oba v it da gale xx jerry effect it cont Qb6 bet! 

Mar2322   landshark: I didn't even bother to find the 'win' here 
....and I'm glad I didn't.
At my level with best play the resulting position is a coin toss. 

Mar2322   TheaN: <landshark: I didn't even bother to find the 'win' here  ....and I'm glad I didn't. At my level with best play the resulting position is a coin toss.> Not really sure what 'best play' you mean. Are you questioning the win? If anything, Qb6 (4) is the only playable move (Rb8 +1), and after some ply a solid 4. The weaknesses in the White camp aren't tough to spot, and potential of the sac itself is kind of obvious. It's a hard Wednesday, but not exceptional. 

Mar2322   NBZ: <NBZ: I found this really difficult, and just could not find Qb6.> Note to self: evidently, I have not changed in the last 4 years! I found this just as difficult. At least I "saw" the Qb6 idea this time, but managed to convince myself it didn't work. Alas. 

Mar2322   King.Arthur.Brazil: If white played 22. ♕xa8 ♖xf4+ 23. ♔e1 ♕e3+ 24. ♔d1 ♕xb3+ 25. ♔c1 ♖c4+ 26. ♔b1 ♔h7 27. g4 ♖c2 28. ♖a2 ♗e6 29. ♕e4 ♖f2 30. ♕d4 ♕xa2+ 31. ♔c1 ♕a1# or 25. ♔e1 ♕e3+ 26. ♔d1 ♖d4+ 27. ♔c2 ♖d2+ 28. ♔b1 ♕d3+ 29. ♔a2 ♕c4+ 30. ♔b1 ♕c2+ 31. ♔a2 ♕xb2#. Only understanding this, 21...♕b6 becomes "easy". I found both 22...♗b7 and felt doubt about 23...g5 my first option and 23...♕xf6 for which I didn't see any winning combination or big line. I hoped that White would commit another mistake, which is 24.fxe7? like "if I'm going to die, let's play some music!" I don't believe 24. ♗d1 ♖ad8 25. ♗f3 would save but has more chances than the game. line Or 24. ♗d1 ♖f4+ 25. ♗f3 e5 26. ♕f2 e4 27. ♕xb6 axb6 28. ♔f2 exf3 29. g3 ♖d4 Black has a ♗ advantage and probably will win. 

Mar2322
  agb2002: White threatens Qxa8 and fxe7.
The position of the white king suggests Qd2, Qb6 and Qc7. The move that stops the maneuver Kg1h2, prepares Bb7 and threats Qxf6 is 21... Qb6: A) 22.Qxa8 Rxf4+
A.1) 23.Ke1 Qe3+ 24.Kd1 Qxb3+ must be winning. For example, 25.Kc1 Rc4 26.Kb1 Kh7 27.Rf1 Qc2+ 28.Ka2 Be6 29.Re1 Re4+ 30.Qd5 Bxd5#. A.2) 23.Ke2 Rf2+ 24.Kd3 (24.Ke1 Qe3+ 25.Kd1 Qd2#; 24.Kd1 Qd4+ and mate in two) 24... Kh7 A.2.a) 25.Qxc8 Qd6+ 26.Bd5 (26.Ke3 Qd2+ and mate in two; 26.Ke4 Rf4+ and mate in two; 26.Kc3 Qd2#) 26... Qxd5+ 27.Kc3 (27.Ke3 Qd2+ and mate in two) 27... Qd2+ 28.Kb3 Qxb2#. A.2.b) 25.fxe7 Bf5+ 26.Qe4 (26.Kc3 Qc5+ 27.Bc4 Qxc4#) 26... Bxe4+ 27.Kxe4 Re2+ is winning. A.2.c) 25.Bd5 Bf5+ 27.Be4 (27.Kc3 Qc5+ 28.Kb3 Qc4#) 27... Qd6+ 28.Kc3 (28.Ke3 Qd2#) 28... Qd2+ 29.Kb3 Qxb2#. A.3) 23.Qf3 Rxf3+ 24.gxf3 Qxf6, with the double threat Qxf3+ and Qxb2, is winning. B) 22.fxe7 Bb7 looks very good for White. For example 23.Qf2 Qd6 (threatens Rxf4 and Rd2) 24.Kg1 Rd2 must be winning. C) 22.Bd5 Qxf6 wins a pawn at least (23.Bxa8 Rxf4). 

Mar2322   Stanco: In a fifteen minutes struggle my calculations have finally reached firstly discarded 21...Qb6 22.Qxa8 Rxf4+ 23.Ke2 Rf2+ 24.Kd3 Qd6+ just to realise after 25.Bd5 a good Sunday has appeared 

Mar2322   johnnydeep: Too tough for me. 

Mar2422
  Check It Out: I didnt even consider Qb6. It made sense as soon as I saw it played. 


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