Mates to squares blocked by white units


It isn't unusual in orthodox twomover that some mating move is impossible because of presence of white unit blocking mating square. Mate in question becomes possible only after this white unit leaves in key or it is annihilated in defence. But only rarely it happens that this kind of mates is shown multiple times in one problem. By chance I noticed some of these among problems sent to Album FIDE 1992-94 and afterwards I looked into Album FIDE 1989-91, where I found another excellent twomover.
Vyacheslav Kopajev
Sachmatnaja kompozicia

1.c7? zz
1...Kd3 (b4), bxc4+ 2.Bc6#, Bxc4#
1...Kc5!

1.e5? zz
1...Kd3 (b4), Kc5 2.Be4#, Qb6#
1...Kxe5!

1.c5? zz
1...Kd3, Ke5 2.Bc4#, Qh8#
1...b4!

1.e7! zz
1...Kd3 (b4), bxc4+, Kc5, Ke5 2.Be6#, Bxc4#, Qc6#, Qh8#

4-phase change of mate after 1...Kd3. There is also the creating of weaknesses in white position leading to refutations in 3 tries, that adds a bit of interest.









#2 (14+4)

Milan Vukcevich
1st Prize Schulte Memorial 1993

1.Rg8? zz
1...Sb5 (Se2), Kd4 2.Kd7#, Rg4#
1...Sd5!

1.d7? zz
1...Se2, Kd4 2.Kd6#, Re4#
1...Sb5!

1.Qd7? zz
1...Sb5, Kd4 2.Ke7#, Qa4#
1...Sd5!

1.Sd7! zz
1...Sb5 (Se2), Kd4 2.Kf6#, Qh4#

Change of 2 mates in 4 phases! Of course, there are banal duals after "weak" moves of knight, e.g. after Sb1 in all phases, but that doesn't matter. Main trick is in the fact that 3 keys simultaneously unblock and block square for wK, pawn, queen and knight arrive at d7. Changed mates after king move are ingeniously arranged too. Two minor flaws: 2 tries are refuted by same move, Re8 plays only in 1st try, then it sleeps.









#2 (16+3)

Hubert Gockel
1st HM Die Schwalbe 1993

1.Sb6? th. 2.Qd4#
1...Be6, Qxf6, Sxf4, Sxb4, c5, Rxe7
2.Qxe6#, Sxc8#, Qxf4#, Qe5#, Qd5#, Qxe7#
1...Bxc3!

1.Qd4! th. 2.Sb6#
1...Be6, Qxf6, Sxf4, Sxb4, c5, Rxe7
2.Se4#, Sxf6#, Sxf4#, Sxb4#, Rb6#, Sxe7#
1...Bxc3, cxd5
2.Sxc3#, Qb6#

The things are little bit crowded around black king and it is mainly lack of space that motivates unexpected change in 6 variations (!) after key and threat reciprocally inverted (!!! - it is possibly the only twomover with this blend of themes - am I right?). In this composition it isn't white who frees squares for lethal mating moves, no, it is black who annihilates blocking white pawns.









#2 (12+11)

Jevgenij Bogdanov
1st Prize Chess Life 1990

1.Rxe3? zz
1...bxc6, gxf3 2.Bxc6#, Bxf3#
1...Bxe6!

1.fxg4? zz
1...exd2, Bxe6 2.Bf3#, Sf3#
1...bxc6!

1.cxb7? zz
1...exd2, Bxe6 2.Bc6#, Sc6#
1...gxf3!

1.Rf6! zz
1...bxc6, gxf3 2.Sxc6#, Sxf3#
1...exd2, Bxe6 2.f4#, Rxe6#

How simple and how efficient! For any of 4 thematical mates Sf3, Sc6, Bc6, Bf3 two of 4 actions must be taken: f3 vacated, potential flight at e6 covered or blocked, c6 vacated, Re2 activated to e5. All keys take care of one of these and white then waits how will black harm himself. In tries one of 4 black defences is removed, so black wisely selects one for refutation, two other are met by above given mates. In solution, however, all 4 black defences are in existence and these two that aren't harmful in expected manner, are followed by completely new mates made possible by special key. Again, how simple and how amazing!









#2 (13+9)

Comments to Juraj Lörinc.
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