py_20181023

{

} a) 1. f5*e6 ep.! g2*f1=Q 2.Rf4-f8# {The white pawn structure requires 7 captures. Black's g2-pawn has captured, which requires the promotion of White's "a" pawn to b8 after a6xb7, i.e. an 8th White capture. white "a" pawn to b8 after a6xb7, i.e. an 8th white capture. But the last move could not be ...h3xg2, which would force White to make two more captures because a pawn comes from h2. The only remaining Black move is either . ...c7-c5, or ...e7-e5. Suppose it was ...c7-c5. Then the Fb8 comes from promotion. The original Fc1 must have been captured by the pawn currently on g2, which is impossible, the capture having been made on a white square (the Pg3 comes from g2). Remains ...e7-e5. This condemns the Ff8, but it is not annoying, there remain 8 black units, including the "d" and "f" pawns captured on their file, the Pg2 coming naturally from h7. The last move was therefore ...e7-e5.

} b) wPf2-->g4 {pf2-->g4} 1. b5*c6 ep. ! e5*f4 2.Qb4-f8# {
In comparison with the twin (see analysis), there is an extra white move (so in total 9 counting axb7), so that Bf8 had to participate. The last move could not be ...e7-e5. On the other hand, ...c7-c5 could (and should) have been the last move, as the Bb8 coming from promotion, because the original Bc1 could be captured by ... h4xg3: the g3-pawn comes from f2 (f3 from e2, g4 from g2). So there was ...hxg3-g2 then f2xg3 and h3-h4-h7.}

{

} a){Camel f1
} 1...CAf1*c2 2.CAf2-c1 CAc2*b5 {clears the way for the Qb7} 3.Rh2-b2 CAb5-e6 4.Kb3-c2 Kf3-e2 5.Qb7-b3 CAe6-f3 # ! {

} b) +wZf1 {Zebra f1
} 1...Zf1*c3 2.Zf6-c4 Zc3*f5 {frees the square e3 for the White King} 3.Bh8-b2 Zf5-h8 ! 4.Kb3-c3 Kf3-e3 5.CAa6-b3 Zh8-e6 # ! {

Note the diagonal-orthogonal echo between Bb2 and Rb2
Of course, many of the units are only used for a twin, this classic flaw is glaring, but the problem is entertaining.
Kniest theme: a black piece is captured on the future mate square.}

{

} 1.Bh2-f4 Sh1-g3 {don't check because of Qb1} 2.Qc2*d1[bQd1->d8] Qb1-b5 # {by double check

} 1.Be4*h1[bBh1->c8] Qb1-b5 2.Qc2-e4 Rd1-f1 # {by double check

} 1.Rb7*b1[bRb1->a8] Rd1-f1 2.Sd7-e5 Sh1-g3 # {by double check

cyclic Zilahi theme AB-BC-CA}

{

} 1.Kd6*d7 e7*f8=PR + 2.Kd7-e8 PRf8-e6 {semi-mirror stalemate

} 1.PRf8*e7 Kf3-e4 2.PRe7-c8 d7*c8=Q {mirror stalemate}

{

} 1.Se5-c4 ? {threatens} 2.Bd5-e4[c6=w] # {
} 1...Bg8*d5 2.Rd6*d5[d4=w][d7=b] # {
} 1...Sd4-e2 2.Qc1-c2[e2=w][b3=w][c3=w] # {
} 1...c6*d5 2.Rd6*d5[d4=w][d7=b] # {
but} 1...Sd4-e6 ! 2.Bd5-e4+ Se6-c5[d7=b][b3=w][e4=b][a6=w] + {et} 2.Bd5*e6[g8=w][d7=b] d7*e6 ! {
} 1.Se5-f3 ? {threatens} 2.Sf3*d4[b3=w][c6=w] # {
} 1...Sd4-e2 2.Qc1-c2[e2=w][b3=w][c3=w] # {
} 1...Sd4*f3 2.Bd5-e4[f3=w][c6=w] # {
} 1...c6*d5 2.Rd6*d5[d4=w][d7=b] # {
but} 1...c6-c5 ! {

} 1.Se5*c6 ! {threatens} 2.Sc6-e7[d5=b][g8=w] # {
} 1...Sd4-e2 2.Qc1-c2[e2=w][b3=w][c3=w] # {
} 1...Sd4*c6 2.Bd5-e4[c6=w] # {
} 1...Rc7*c6 2.Rd6*f6[c6=w] # {
} 1...Rc7*d7 2.Sc6*d4[b3=w] # {
as the rook has left the file, there is no longer the Rc4+ parry that would blacken the knight

"Tertiary threat correction".}

{

tries :
} 1.Se7-c8 ? {threatens} 2.Rc7-e7 # {
} 1...e3-e2 2.Qc2*e2 # {(Ne5 is illegal) but not} 2.Rc7-e7 + {because of} e2-e1=R {
but the good défence is} 1...Qg6-g3 ! {
} 1.Se7*c6 ? {threatens} 2.Sc6-d4 # {since ...Nd8 & ...Ng5 illegal but neither} 2.Rc7-e7 + ? Rb6*c6 ! {, nor} 2.Rd5-d6 + ? Ke6-e5! { since the Nc6 is pinned)}
} 1...Rb6-b1 2.Rc7-e7 # {but not} 2.Sc6-d4 + ? Rb1-d1 ! {
the good défence is} 1...Qg6-g4 ! {

} 1.Se7*f5 ! {threatens} 2.Qc2-e4 # {(Ne5 is illegal) "Tertiary threat correction".(note that } 2.Rc7-e7 {don't checkmate because } Ke6*e7 ! {
} 1...Qg6-g3 2.Sf5-d4 # {(note that} 2.Qc2-e4 + {don't checkmate because } Qg3-d6 ! {)
} 1...Qg6-g4 2.Rc7-e7 #

{

} a) {
} 1.d7-d8=R e2-e1=B 2.Rd8*d4 c2-c1=Q 3.Rd4-h4 + Be1*g3 # {
(Ici} 2...c2-c1=R 3.Rd4-h4 + Be1*g3 {would not checkmate because } 4.Be5-b2 {would paralyze the Rook)

} b) +bPh5 {+bPh5
} 1.d7-d8=B e2-e1=S 2.Bd8*e7 c2-c1=R 3.Be7-g5 + Se1-f3 # {
(and as in the a,} 2...c2-c1=Q 3.Be7-g5 + Se1-f3 {would not checkmate because } 4.Rg7-c7 {would paralyze the Queen)}

{

} 1.Sb1-a3+ ? Kc4-c3 {
} 1.Rg2*e2 ? {(bB ad libitum) does not threaten} 2.Re2-c2 {since ... } Sf8*h7[+wPc3] {

} 1.Rg2*g5[+bPa3] ! {The threat is } 2.Sb1*a3[+bPc3] # {
Black parries it by placing a white pawn on c3 so that there can be no black pawn! But there will be a damage:
the control by the said pawn of the square d4.
} 1...Sf8*d7[+wPc3] 2.Qe4*e2[+bBd5] # {
} 1...Sf8*e6[+wPc3] 2.Qe4*e6[+bSd3] # {(A noter que} 2.Qe4*e2[+bBd5] ? {is not mat because of} Se6*g5[+wRd3] ! {and not} 2...Se6*d4 {because the wP cannot be moved back to d3
} 1...Sf8*h7[+wPc3] 2.Qe4*c6[+bPd3] # {and here,} 2...Sh7*g5 {is impossible because one cannot replace wR on c5
} 1...Be2-f1 2.Sb1*a3[+bPc3] #