Friday, April 11, 2008

Multiple Grimshaw Intersections

The great composer Loshinsky created the following problems, each containing three Grimshaw intersections:

 (Problem 35) Lev Ilych Loshinsky, ”L' Italia Scacchistica”, 1930 White plays and mates in 2 moves #2 (10+8) [5S2/2K2B2/P1p3r1/1pk5/1S5R/2pP3b/r1Q4B/b4R2]

Problems having many tries make the life of solvers difficult, but here the situation is rather simple:
Tries: {1.Sd7+? Bxd7!}, {1.Se6+? Rxe6!}, {1.Sxg6? Bg4!}, {1.Bxg6? Bg4!}, {1.Rc4+? bxc4!}, {1.d4+? Kxb4!}, {1.Bg1+? Rxg1!}, {1.Bd6+? Rxd6!}, {1.Qxc3+? Bxc3!}, {1.Qf2+? Rxf2!}, {1.Rf5+? Bxf5!}.

Key: 1.Rb1! [2.d4#]
Now every defense creates a Grimshaw interference, and the black can not take the white piece that gives mate. The black defenses and the white continuations are:

Grimshaw intersection at e6
1...Re6 2.Sd7# (2...Bxd7 is not possible).
1...Be6 2.Bd6# (2...Rxd6 is not possible. Another black defense, 1...Rd6, results in a similar mate picture after 2.Bxd6#).

Grimshaw intersection at g4
1...Rg4 2.Se6# (2...Bxe6 is not possible).
1...Bg4 2.Bg1# (2...Rxg1 is not possible).

Grimshaw intersection at b2
1...Rb2 2.Qxc3# (2...Bxc3 is not possible).
1...Bb2 2.Qf2# (2...Rxf2 is not possible).

The second orthodox two-mover by Loshinsky presented here, is one of the famous chess problems because it is a complete block.

 Theme Complete block : In the initial position, any black move can be answered with mate by the white.

 (Problem 36) Lev Ilych Loshinsky, ”Tijdschrift v. d. Nederlandse Schaakbond”, 1930 White plays and mates in 2 moves #2 (6+7) [b3K2b/r1R2p1r/4k3/1S1s4/2BP1Q2/8/8/8]

There are several tries: {1.Kd8? Bf6+!}, {1.Rc6+? Bxc6+!}, {1.Rxa7? Bc6+!}, {1.Rb7? Rxb7!}, {1.Re7+? Rxe7+!}, {1.Qd6+? Kf5!}, {1.Qe5+? Bxe5!}, {1.Qe4+? Kf6!}, {1.Qxf7+? Rxf7!}, {1.Qf5+? Kxf5!}, {1.Ba2? Rxa2!}.
Key: 1.Bb3!
The key preserves the blocked position, does not threatens anything, but black finds himself in a zugzwang situation. Black has six thematic defenses on three intersections and we see two simple Grimshaws and a pawn Grimshaw:

Grimshaw intersection at b7
1...Rb7 2.Rc6# (2...Bxc6 is not possible).
1...Bb7 2.Re7# (2...Rxe7 is not possible).

Grimshaw intersection at g7
1...Rg7 2.Qe5# (2...Bxe5 is not possible).
1...Bg7 2.Qxf7# (2...Rxf7 is not possible).

Pawn Grimshaw intersection at f6
1...Bf6 2.Qg4# (2...f5 is not possible).
1...f6 2.Qe4# (2...Be5 is not possible).

There are some more, not thematic, defenses of black :
1...f5 2.Qd6#, 1...Rxc7 2.Sxc7#, 1...Bxd4 2.Sxd4#.

[This post in Greek language].