py_20231121

Furman, J.
2023

black Pf4b7e4h2 Rh8 Ke8 white Ba5h3 Pb6d2f2e5g4f5g5h5 Rd4f3 Sd3h1 Kh4

h=2 a posteriori(15+6)

: a move is justified by a later one (a posteriori)

A dissection of the position below: 1) B can only play fxg3 e.p. if they can prove that W last move can only be g2-g4 2) because of the retrograde analysis developed in point 4, for W last move to be necessarily g2-g4, B must have retained the right to castle (because if they played K or R, the position can be obtained without W last move being g2-g4). 3) The only way for the Ns to prove they have the right to castle is to castle (during the solution, but not necessarily on the first move. This is the principle of "a posteriori" chess). 4) White has made 9 pawn captures, corresponding to the 9 missing black units other than the Ph7. Ph2 comes from g7 after taking the White Queen, the only missing White unit, and so Pe4 cannot come from d5.
It is Black to move, and the last white move could not have been a capture.
The only condition for castling to be legal is that it must have been g2-g4, following ...g3xQh2. But if the en passant move is considered legal Black must justify the legality A POSTERIORI by castling.
Hence the solution
{

} 1.f4*g3 ep. Rf3*g3 {(or, it seems, fxg3 or Kxg3)} 2.e4*d3 Ba5-b4 {!! stalemate.

Since Black has to castle, he is not allowed to play the King or the Rook otherwise, so he is stalemated. !

Argumentation accepted by judge Michel Caillaud, who gave this problem a 1st honorable mention at the 2023 "Champagne" competition.,
while expressing his delight at hearing from Janko Furman after...50 years !}

2 - 2# circe

Cheylan, Y.
1986

white Qf6 Pf5e6e5d3c4b4 Be4f4 Rc1 Sa2 Kh2 black Pe7h6b5a6 Qf8 Ba4 Sa5 Kd4

#2 circe(12+8)

: A captured piece is reborn on its original square if it is free.

Solution

{

} 1.Rc1-b1 ? {or}1.Rc1-a1 ? {(threatens } 2.Bf4-e3 # {)
} 1...Qf8*f6[+wQd1] ! {and there is no 2.Qa1 #
} 1.Rc1-g1 ? {or} 1.Rc1-f1 ? {or} 1.Rc1-e1 ? {(threatens } 2.Bf4-e3 # {)
} 1...e7*f6[+wQd1] ! {and there is no 2.Qg1 # and } 2.Qd1-a1 + {is parried by} Qf8*b4[+wPb2] ! {
} 1.Rc1-c2 ? {(threatens } 2.Bf4-e3 # {)
} 1...Sa5*c4 ! {and as there is no pawn rebirth on c2, there is no 2.c2-c3#.
} 1.Qf6-h4 ? {(threatens} 2.Qh4-f2 # {)
} 1...Qf8*f5[+wPf2] ! {

} 1.Rc1-h1 ! {(threatens } 2.Bf4-e3 # {)
} 1...Qf8*f6[+wQd1] 2.Qd1-a1 # {(and not } 2.Qd1-g1 + Qf6*f5[+wPf2] ! {)
} 1...e7*f6[+wQd1] 2.Qd1-g1 # {(and not } 2.Qd1-a1 + Qf8*b4[+wPb2] ! {)
} 1...Sa5*c4[+wPc2] 2.c2-c3 # {

Loyd clearance (for d1-a1) and Bristol clearance (for d1-g1).}

3 - 8# with paos & vaos

Werner, D.
2020

white WPe7 Ph3 Bg1 Sf2 Kf4 WVe8 Rd1 black BPh7 BVg3a2 Ph4g2h6f6f5b3c3 Sb1 Ke2

#8(7+6)
🨵e7, 🨻h7: Pao
🨶e8, 🨼g3, a2: Vao

: Rook needing a hurdle to capture
: Bishop in need of a hurdle to capture

Solution

{

} 1.WVe8-c6 ? {(threatens} 2.WVc6-e4 # {)
} 1...b3-b2 ! 2.WVc6-e4 + BVa2-e6 ! 3.WVe4-d5 + BVe6-f7 ! 4.WVd5-e6 + BPh7*e7 ! {or} 4.WPe7-e6 BVf7*d5 ! {
Or} 2.WPe7-e6 ? BVa2-d5 ! {: Vao has no access to e4.
The plan is to exert the same threat with the Vao on f3 instead of c6.
} 1.WVe8-d7 ? Sb1-d2 ! 2.WVd7-e6 + Sd2-e4 {, or } 1...BPh7*d7 ! {

} 1.WPe7-g7 ! {(threatens} 2.WPg7*g2 # {)
} 1...BVg3-h2 {(} 2.WVe8-h5 ? BPh7*h5 ! {)
} 2.WVe8-g6 ! {(same threat)} BVh2-g3 3.WVg6-h5 ! BVg3-h2 4.WVh5-g4 ! {(4.Vf3? Nd2!)} BVh2-g3 {
} 5.WVg4-f3 ! {(Vao will now have access to e4)} BVg3-h2 6.WPg7-e7 ! {(back ; threatens} 7.WVf3-e4 # {)
} 6...b3-b2 7.WPe7-e6 ! BVa2-d5 8.WVf3-e4 #

4 - 3# with equihopper and fers

Bennett, E.
1948

white WFb8 Pa6 Sc6 Ka1 EQg2 black Ka8 Pf7 BFf4

#3(5+3)
🨶b8, 🨼f4: Fers
🩈g2: Equihopper

: piece that plays symmetrically with respect to any unit, as long as it stays on the chessboard
: bouncer (1,1)

Solution

{

} 1.WFb8-c7 ! {
} 1...f7-f6 {ou} 1...f7-f5 2.EQg2-e6 # {
} 1...BFf4-g5 2.EQg2-g8 {and} 3.WFc7-d8 # {
} 1...BFf4-e5 2.EQg2-c8 {and} 3.WFc7-b8 # {
} 1...BFf4-g3 2.EQg2-g4 {and} 3.WFc7-d6 # {or} 2...f7-f5 3.EQg4-e6 # {
} 1...BFf4-e3 2.EQg2-c4 {and} 3.WFc7-b6 # {

Star of each Fers}

5 - 2# bicolores

Tylor, Ch
2020

white Pd6c5d2h2 Kf1 Qg3 black Kf6 Qh7 Pd3h3

#2 bicolores(6+4)

: In Bicolores, a King is also in check by the units of his own camp.

Solution

{

} 1.d6-d7 ! {(blocus)
} 1...Qh7*d7 2.Qg3-g7 # {
} 1...Qh7-g8 2.Qg3-g5 # {
} 1...Qh7-h5 2.Qg3-e5 # {
} 1...Qh7-e4 2.Qg3-g6 # {
} 1...Kf6-e6 2.Qg3-d6 # {

4 mates on double-guarded squares in Orthodox chess.
Black Queen is like White Queen, except that it can only be played by Black. !}

6 - h#3 2 sol celle with neutral pieces

Tritten, P.
2019

neutral Bc3 Sh7 black Kf2

h#3 celle 2sol.(0+1+2)

: In Celle (= cell, ermitage), a capturing unit ipso facto spawns an identical unit on the square it has just left.
This also applies to Kings, who are then Siamese. :
a side is checkmated if only one of its Kings can escape check.
: A neutral piece can be used by either side

Solution

{

} 1.nSh7-f6 nBc3*f6[+wBc3] {
: the neutral bishop plays as white, so a white bishop reappears, not a neutral bishop !
} 2.Kf2-g3 nBf6-h4 + 3.Kg3*h4[+bKg3] Bc3-e1 # {

} 1.nBc3-f6 nSh7*f6[+wSh7] {
(the neutral knight plays as white, so a white knight reappears, not a neutral knight.)
} 2.Kf2-f3 nSf6-e4 3.Kf3*e4[+bKf3] Sh7-g5 #

7 - h#4 2 solutions PWC Einstein chess

Stun, J.
2019

white Pf4 black Kd4 Pe5e3 Bd3

h#4 2sol.(1+4)
Circé échange
Einstein

: A captured piece is reborn on the departure square of the capturing move

: a unit (other than the King) changes at each move to the next strongest unit in case of capture ,
immediately less strong when no capture.

Solution

{

} 1.e3-e2 {Stay a pawn, for there is no weaker !} f4*e5=S[+bPf4] 2.Kd4-e3 Se5*d3=B[+bBe5] {
} 3.Be5-d4=S Bd3*e2=R[+bPd3] + 4.Sd4*e2=B[+wRd4] Rd4*f4=Q[+bPd4] # {
Of course,} 5.Ke3*f4[+wQe3] {impossible.

} 1.Bd3-c4=S f4*e5=S[+bPf4] 2.Sc4*e5=B[+wSc4] Sc4*e3=B[+bPc4] + {
} 3.f4*e3=S[+wBf4] Bf4*e3=R[+bSf4] 4.Sf4-d3=P Re3*e5=Q[+bBe3] # {

Echo Mates.
The f4 pawn returns (to f4 or e5) to mate, having won its marshal's baton..}

8 - h#2 2 solutions masand

Gockel, H.
2019

white Pc2d3c3 Ke4 black Qd1 Se2 Ka2 Rb5 Pc4a3

h#2 masand 2sol.(4+6)

: all units attacked by the checking unit change color.
Except, of course, the King.

Solution

{

} 1.Se2*c3[d1=w][b5=w] + Qd1-a1[c3=w] + 2.Ka2*a1 Rb5-b1 # {

} 1.Qd1*d3[c2=b][e2=w][c3=b][c4=w] + Ke4*d3 2.Rb5-b1 Se2*c3[b1=w] # {

Double arabian mate} {
}

9 - h#2 5 solutions anti-circe with nightriders

Caillaud, M.
2008

white Kh8 Qh6 Pg7g6f6e3 WNc6 black Pd2b2d4f5g5 Bh4 BNf1h1 Rg1f3 Se4d5 Qe5 Kg4

h#2 anti-circe 5sol.(7+14)
🨢c6, 🨨f1, h1: nightriders

: after a capture, the capturing piece returns to its original square if it is free
If the square is busy, the capture is illegal.
If the capture and rebirth square is the same, the capture is authorized in Calvet and forbidden in Cheylan.
: Extended knight

Solution

{

} 1.Rf3-h3 g7-g8=Q 2.Qe5-g3 Qg8*d5[wQd5->d1] # {
} 1.BNh1-g3 {display-departure-file} g7-g8=R 2.Qe5-e8 Rg8*e8[wRe8->h1] # {
} 1.BNf1-g3 {display-departure-file} g7-g8=B 2.Qe5-e6 Bg8*e6[wBe6->f1] # {
} 1.Rg1-g3 g7-g8=S 2.Qe5-e7 Sg8*e7[wSe7->g1] # {
} 1.Bh4-g3 g7-g8=WN 2.Qe5*f6[bQf6->d8] Ng8*e4[wWNe4->e8] # {

} {
}

10 - h#2 transmuted Kings

Packa, L & Kekely L
2017

white Pd7 Qg7 Ke6 black Kf4 Pe2

h#2 transmuted Kings(4+6)
b) Ke6-->f6

: King acquires the march of the unit which gives him check.

Solution

{

} a) {
} 1.e2-e1=S d7-d8=R 2.Se1-f3 Rd8-d4 # {

} b) wKe6-->f6 {Ke6-->f6
} 1.e2-e1=Q d7-d8=B 2.Qe1-e3 Bd8-c7 # {

Hypereconomical AUW}

Add a comment

Name

E-mail

Website