No. 50, Apr-Jun 2010
R0160 - Paul Raican, Vlaicu Crisan
StrateGems 50, Apr-Jun 2010
(Misprint fixed)
9+5. -9 & s#1, Proca retractor, Circe assassin
[r1Bk4/6P1/3r2P1/6PR/5PP1/4b2K/8/1q5N]
Solution
A highly specific and difficult idea: the bK stands on the rebirth square of the bQ, who is on the rebirth square of the wS. In the forward play, Qb1 is threatened and has no flight, so the only defense, preventing the king’s assassination, is her suicide. The black rooks appear on the h file by Circe Assassin specific uncaptures, also showing neat dual avoidances, namely -2.Rh2xRh5(+bRa8,-wRa8)? or -2.Rh4xRh5(+bRa8,-wQa8)?. Thematic content: Three suicides, two in the retro play (wRa8: passive - wQe5: active) and one in the forward play (bQb1: passive) - The same black rook visits 3 corners (a8, h8 and h1) - Active self-blocks of bQb1 in the retro play (bRd3, bBc1). A real Circe Assassin show! (A)
R0161 - Valery Liskovets
7+12. hc#2.5 (2 solutions)
[r3k3/Pp1p2pp/1p1p4/3Pp3/R2r4/nB2p1K1/4P1P1/8]
1...Bc2 2.Sxc2 Rxd4 3.0-0-0! Rc4# ii) 1...Bd1 2.Rxd1 Rxa3 3.0-0-0! Rc3#.
Due to wPe2, g2 and bPb7, d7, g7, h7, the white bishop must be promoted (on e8, or g8 via f7). So, castling is illegal, if the wB remains on the board and these pawns occupy their initial squares. Castling becomes legal, according to the consequent rules, when one of these conditions no longer exists,. Retro motivated active sacrifices of the wB. Model mates by the wR on different squares (A).
R0162 - Joaquim Crusats, Andrei Frolkin
13+11. -13 & #1, Proca retractor
[rR4bk/p2PpprN/3p1pP1/7B/8/3P1PPR/PP1KPp2/6n1]
Try: -1.Sg5-h7? Rh7-g7 -2.Bg4-h5 & 1.Rxh7# but -1…Bh7-g8! Solution: retract: -1.Rc8-b8 Rb8-a8 -2.Kc2xRd2 Rd1-d2+ -3.Kb3-c2 Ra8-b8+ -4.Kc2xPb3 b4-b3+ -5.Kc1-c2 Rd2-d1+ -6.Rb8-c8 b5-b4 -7.Bg4-h5 b7-b5 (-7....b6-b5 -8.Bh5-g4 b7-b6 -9.Sg5-h7 Rh7-g7 -10.Bg4-h5 & 1.Rxh7#) -8.Kc2-c1 Rd1-d2+ -9.Kb1-c2 Rd2-d1+ -10.Bh5-g4 Rc2-d2 -11.Kc1-b1 Rd2-c2+ and now the main plan works: -12.Sg5-h7 Rh7-g7 (now -12....Bh7-g8 is illegal) -13.Bg4-h5 & 1.Rxh7#
Single line dual-free Proca retractor with logical play. Black is in retro-stalemate. The main plan enables two retractions, one being a refutation. White needs a fore-plan to illegalize the refutation move while keeping black in retro-stalemate. (A)
R0163 - Nikolai Beluhov
15+12. Mate?
[8/pB3P2/8/PPPp4/r1RPp3/n1QpP1P1/rnkN1Pp1/BRqbK3]
The position is legal and mate. Retract: -1.Qb4xQc3+ e5-e4 -2.Se4-d2 Qb3-c3+ 3.Sc3-e4+ d6-d5 -4.Bf3-b7 d7-d6 -5.Be2-f3 e6-e5 -6.Bf1-e2 e7-e6 -7.e2-e3 Qh6-c1 -8.f6-f7 Qh1-h6 -9.f5-f6 h2-h1Q -10.f4-f5 h3-h2 -11.h2xBg3 Bh4-g3 -12.f3-f4 g3-g2 -13.Bg2-f1.
The last 25 single moves are exactly determined, except for the order of the black pawns’ retraction in moves 4-6. (A).
R0164 - Nikolai Beluhov
(Misprint corrected)
14+13. Last move?
[B1N5/Prpp4/QbkPP3/ppNRp1P1/3p4/KP4B1/RrP4p/qb6]
Tries: -1.Bf4-g3 h3-h2 -2.g4-g5 h4-h3 -3.Bh6-f4 h5-h4 -4.Bf8-h6 h6-h5 -5.f7-f8B h7-h6 -6.f6-f7, or -1.Se4-c5 h3-h2 -2.Sf6-e4 h4-h3 -3.Sh7-f6 h5-h4 -4.Sf8-h7 h6-h5 -5.f7-f8S h7-h6 -6.f6-f7 are one move too slow. Solution: retract: -1.Be1-g3 h3-h2 -2.Bb4-e1 Rb8-b7 -3.Sb7-c5+ Bc5-b6 -4.Sb6-c8+ Rf8-b8 -5.g4-g5 Rf3-f8 -6.g3-g4 Rc3-f3 -7.g2-g3 Rc4-c3 -8.Bd2-b4 Rb4-c4+ -9.Bh6-d2 h4-h3 -10.Bf8-h6 h5-h4 -11.f7-f8B h6-h5 -12.f6-f7 h7-h6 -13.f5-f6 f6xBe5 -14.B~-e5 f7-f6 -15.Re5-d5 d5-d4.
In order to provide the extra move, white must confine both of his mobile pieces. (A)
P0263 - Gennadi Zgerski, Rustam Ubaidullaev
14+14. Proof game in 10.5 moves
[r1b3nr/pp1pp1b1/4p1p1/2q4k/7p/8/PPP2PPP/RNBQKBNR]
1.e4 h5 2.e5 h4 3.e6 fxe6 4.d4 Kf7 5.d5 Kg6 6.Qh5+ Kxh5 7.d6 g6 8.dxc7 Bg7 9.cxb8Q Qb6 10.Qd6 Qc5 11.Qd1#
P0264 - Unto Heinonen
16+6. Shortest proof game in 11.0 moves (Take&Make)
[5k2/5p2/3pp3/2n5/8/7b/PPPPPPPP/RNBQKBNR]
1.a4 b5 2.axb5-b4 g5 3.Rxa7-a6 Bh6 4.Rxh6-g7 d6 5.Rxh7-h5 Bh3 6.Rxg5-g4 e6 7.Rxg8-e7+ Kf8 8.Rxc7-c5 Rh5 9.Rxh5-a5 Sd7 10.Rxa8-a1 Qa5 11.bxa5-a2 Sc5.
White's initial position (A)
P0265 - Mario Parrinello, Kostas Prentos
13+14. Shortest proof game in 21.5 moves
[2bkBbnr/1pp1pppq/QpN1pB1p/8/4N1K1/P1P2PP1/P2P2P1/8]
1.f3 Sc6 2.Kf2 Sd4 3.Kg3 Sxe2+ 4.Kg4 Sg3 5.hxg3 Rb8 6.Rh6 Ra8 7.Rb6 axb6 8.Qe2 Ra5! 9.Qa6 Ra3 10.bxa3 h6 11.Bb2 Rh7 12.Bf6 Rh8 13.Sc3 Rh7 14.Re1 Rh8 15.Re6 dxe6 16.Sge2 Qd3 17.Sd4 Qh7 18.Se4 Kd7! 19.Bb5+ Kd8 20.Be8 Bd7 21.c3 Bc8 22.Sc6
The tries 8…Ra3? and 18…Kd8? would leave bRh8 and bBc8, respectively, on the wrong squares. Black needs to lose a tempo twice (8…Ra5 and 18…Kd7), whereas three different black pieces (Ra8, Rh8, Bc8) kill time by oscillation.
P0266 - Rustam Ubaidullaev
16+14. Shortest proof game in 22.0 moves
[3k2n1/3q1pp1/1p1pRn1B/p3p2p/r1p1rP2/2P2B2/PPP2PPP/1N1QK1NR]
P0266 (Ubaidullaev) 1.Sc3 e5 2.Sd5 Bb4 3.Se7 Bc3 4.dxc3 h5 5.Qd4 Rh6 6.Qg4 Ra6 7.Bh6 Ra4 8.Rd1 a5 9.Rd6 Ra6 10.Re6 Rd6 11.Sf3 b6 12.Sd2 Bb7 13.Sb1 Bf3 14.exf3 Rdd4 15.f4 d6 16.Qd1 Sd7 17.Be2 Sdf6 18.Bf3 Qd7 19.Sf5+ Kd8 20.Sg3 c5 21.Se2 c4 22.Sg1 Re4+
After screening on e7 against check, wSb1 must return home. However, it turns out that e7 is closer to g1 than b1; so the other knight goes to b1 when time permits, to clear g1 for its sibling.
P0267 - Gianni Donati, Olli Heimo, Joose Norri
13+13. Shortest proof game in 23.0 moves
[rn2k1nr/P1ppp2p/1p2Bp2/p2p1P2/P3P3/4KN2/2PPP2P/1NB5]
1.a4 a5 2.Ra3 Ra6 3.Rf3 Rg6 4.Rf6 gxf6 5.b4 Bh6 6.b5 Be3 7.f4 Ba7 8.b6 Sa6 9.bxa7 b6 10.Kf2 Bb7 11.Ke3 Bf3 12.gxf3 Qa8 13.Bh3 Qe4+ 14.fxe4 Sh6 15.Sf3 Rgg8 16.Qg1 Rf8 17.Qg4 Sg8 18.Qe6 fxe6 19.Rg1 Kf7 20.Rg5 Ra8 21.Rd5 exd5 22.Be6+ Ke8 23.f5 Sb8.
In order to vacate a8 for the queen, bRa8 takes an eventful round trip.
P0268 - James Soliman
15+13. Shortest proof game in 23.0 moves
[7k/p1p3pn/4rb2/Kp1p4/8/2q1Pb2/nPPPPpPP/RNBQ1BNR]
1.Sc3 f5 2.Sd5 f4 3.Sxe7 f3 4.Sd5 Qf6 5.Sc3 Be7 6.Sb1 Qc3 7.Sh3 Sf6 8.Sg5 0-0 9.Sxh7 Re8 10.Sg5 Sh7 11.Sh3 Bf6 12.Sg1 Re3 13.fxe3 d5 14.Kf2 Bg4 15.Kg3 f2 16.Kf4 Bf3 17.Kf5 Sc6 18.Ke6 Re8+ 19.Kd7 Re6 20.Kc8 b5 21.Kb7 Kh8 22.Ka6 Sb4+ 23.Ka5 Sxa2+
P0269 - Silvio Baier
16+14. Shortest proof game in 27.5 moves
[2nb1q2/8/n5b1/1rrppp2/p6k/2p4p/RRPPPPRR/RNBQKBNR]
1.a4 c5 2.a5 c4 3.a6 c3 4.axb7 a5 5.h4 a4 6.h5 Ra5 7.h6 Sa6 8.hxg7 h5 9.b8R h4 10.Rb3 Rhh5 11.Rba3 Rhc5 12.b4 e5 13.b5 Ke7 14.b6 Kf6 15.b7 Se7 16.g8R d5 17.Rg3 Bf5 18.Rgh3 Kg5 19.R3h2 h3 20.g4 Kh4 21.g5 Sc8 22.g6 Be7 23.g7 Qf8 24.g8R Bd8 25.Rgg2 Bg6 26.b8R f5 27.Rb2 Rab5 28.R3a2
Fourfold Rundlauf with promotions to rooks (A) Compare with P1080465 (Per Olin) in PDB: http://www.softdecc.com/pdb/index.pdb
