py_20190108

{

} a) {Black pawns have made 3 captures, corresponding to the 4 white units units (the Bf1 having been captured at home). It follows that, the Bf8 having was also captured at home, the Bh4 comes from a promotion without change of file (so ...h2xg1=B impossible). The only possibility is that of the The only possibility is that of the a7-pawn in a1 (the Pb5 coming from c7), which has broken the grand-rook.

} 1.0-0 ! threat: 2.Rf1-f8 # {

} b) wPc2-->b2 {As in the twin, Bh4 can only come from a promotion without change of file. The only possibility is the promotion of Pc7 to c1 (the Pb5 coming from a7), since a Ba1 would have been walled in. But this requires that the c2-pawn to have made two captures to get to c7. That is a total of 6 captures by white pawns. Now, 7 black units are missing, including the Bf8 which has never played. The participation of the Ph7 is thus necessary: it had to promote in h1, breaking the small-rook.

} 1.0-0-0 ! threat: 2.Rd1-d8 #

{

Tries :
} 1.Bd3-f1 ? {threatening} 2.d2-d4 # {because Pe4, paralyzed by Qc2, cannot capture "en passant"} 1...Rb6-b7 ! 2.d2-d4 + Qd7-g7 {!!
} 1.Bd3-c4 ? {threatening} 2.Rg5*d5 # {(but not} 2.d2-d4 + ? d5*c4 {!! paralysing the Pd4 by bQ, while Rg5 is paralyzed by Bc1)} 1...Sb1*a3 ! {paralysing Bc4.( But definitely not} 1...Sb1*d2 ? {which is illegal as it frees the Ba3)} 1...Rb6-d6 2.d2-d4 # {by intercepting the bQ making it inoperative} 2...d5*c4 {.
} 1.Qc2*b1 + ? Bc1*a3 ! {

} 1.Bd3*e4 ! {threatening } 2.Se1-d3 # {but neither} 2.d2-d4 + ? d5*e4 ! {paralysing the pawn with Qd7, nor} 2.Rg5*d5 + ? Bh1*e4 ! {paralysing the Rook
} 1...Bh1*e4 2.d2-d4 # {
} 1...Bh1-g2 {(parries the threat because the Knight, by moving away, would no longer paralyse the Bg2)} 2.Rg5*d5 # {(because precisely the bB is immobilised)} 2.d2-d4 # {
} 1...Bc1*d2 2.Qc2*b1 # {
} 1...Rb6*b5 2.Ra7-c7 # {
"Tertiary threat correction".}

{

Essai :
} 1.LEd5*b3 + ? BPb6*b3 ! {
The whole preamble will therefore consist in moving the Pao away from the b6 square

} 1.LEd5-f5 + {Leo f5 allows Eq f1 to check, but now the latter leaves the e3 square.
} 1...Kf3-e3 2.WPd7-d5 + {Eq retakes this square but leaves e4.
} 2...Ke3-e4 3.LEf5-d7 + Ke4-f3 4.Ka8*b7 {
(threatening} 5.LEd7-c6 # {, and here we can't parry by } 4...BPb6-e6 ? 5.LEd7-c6 + BPe6-e4 6.WPd5-f5+ Kf3-e3 7.LEc6-d5 # {)
} 4...BPb6-c6 5.LEd7-f5 + {(retour)} Kf3-e4 6.WPd5-d7 + Ke4-e3 7.LEf5-d5+ Ke3-f3 {
(diagram with the Pao b6 in c6 and incidentally the wK in b7)
} 8.LEd5*b3 # ! {
The e3 square is still controlled, not by the Eq but by the Leo.
Chinese dance on the triangle d5-f5-d7 to keep the black Pao away.}

{

} a) {
} 1.Kd1-e1 WGa7-a5 2.BGa6-e2 Kd3-c2 3.BGa3-a6 Kc2-c1 4.BGa6-f1 WGf2-d2 # {

} b) +wKAa7 +wKAf2 +bKAa6 +bKAa3 {Grasshoppers --> Kangourous
} 1.Kd1-c1 WKa7-a2 2.Kc1-b2 WKa2-g2 3.Kb2-a2 Kd3-c2 4.BKa6-a1 WKg2-b2 #

{

White to move, plays the black King :
} 1...Ka8-b8 # {checkmate the same black King, as the return} 2...Kb8-a8 {is illegal and } 2...Kb8-a7 {(as } 2...Kb8*c7 {) would be expanded. checkmate by double check, Black can't reply} 2.Rb6-c6 {because they are still in check by the white King.

Black to move, plays the white King :
} 1.Kc7-b7 {checkmate the same white king, as the return} 2.Kb7-c7 {is illegal and} 2.Kb7-a6 {or} 2.Kb7-c6 {or} 2.Kb7-c8 {(as Kxa8) would be expanded.}

{

} a) {
} 1...PAb7-b6 ! 2.CAe5*b6[+wPAa6] VAd8*b6[+bCAe4] 3.Qc7*b6[+wVAa7] Sc8*b6[+bQe5] # {

} b) bCAe5-->d4 {e5 --> d4
} 1...VAd8-e7 ! 2.CAd4*e7[+wVAf8] PAb7*e7[+bCAc4] 3.Qc7*e7[+wPAe8] Sc8*e7[+bQd4] # {

Echo checkmates after 4 successive captures on the same square.}

{

} a) {
} 1.e2-e1=B d7*c8=R 2.g2-g1=Q f7*e8=S # {(paralyse Nd6 to prevent } 3.Sd6-e4 {)
Sur } 1.e2-e1=S ? d7*c8=R 2.g2-g1=Q f7*e8=S + {doesn't checkmate :} 3.Se1-g2 {or} 3.Se1-f3 {

} b) -wQg8 -bQh8 {without Queens g8 and h8
} 1.e2-e1=S d7-d8=B 2.g2-g1=R h7-h8=Q # {
note that} 2...h7-h8=R + ? {doesn't checkmate because of } 3.Rg1-g8 ! {

Double AUW.}