Wednesday, April 16, 2008

Grimshaw in 2 and in 3 phases

(Problem 38)
Janos Kiss,
Second Prize, ”Probleemblad”, 1953
White plays and mates in 2 moves. (Set play).
* #2 (12+11)

The asterisk [*] in the problem stipulation shows that there exists set play, thus there are at least two phases:

First phase: Looking at the position on the chessboard, we observe that, in some black moves the white has ready answers with mates. This is called set play.
* 1...Rb6 / Bb6 / Re2 / Be2
2.Sxc5# / Bxc6# / Qf3# / Qe3#

Second phase: We perform the key – move. If the black defending play the same moves, as in the first phase, and the white change the answers that give mate, this is a very good element of the problem.
Key: 1.Qxc5! (Black is in zugzwang situation).
1...Rb6 / Bb6 / Re2 / Be2
2.Qd4# / Qxc6# / Sf6# / Re3#
We see four changed mates on a double Grimshaw, which is a very important achievement of the composer.

Theme Mutate (Changed Mates) : In at least two phases of play, for the same defensive black moves, white changes the moves that give mate

Comment : The problem has some weak points:
(a) The key captures pawn c5, trying to achieve zugzwang situation.
(b) There is an unprovided check (1...Bxg4+), for which there is no set mate before the key. Thus the key (obviously) must protect Be5, so the move (2.Rxg4) can give mate.

Let us see now Grimshaw in three phases of the solution:

(Problem 39)
Mircea Manolescu,
First Prize, Meredith section ”Revista de Sah”, 1956
White plays and mates in 2 moves. (Set play).
* #2 (7+5)

The solution of this problem has three phases. There is set play before the key, there is trial play after a try, and there is actual play after the key.

First Phase: (*) 1...Bc3 / Rc3 2.Se3# / Se5# (Grimshaw intersection at c3)

Second Phase: Try: 1.Sf2? [2.Qb4#] Rb3!
1...Bc3 / Rc3 2.Qd3# / Qf4# (the mates on Grimshaw intersection are changed)

Third Phase: Key: 1.Be3! [2.Rb4#]
1...Bc3 / Rc3 2.Qe2# / Qd4# (the mates on Grimshaw intersection are changed again)
1...Rb3 / Rd3 / Rxe3 2.Rc5# / Qb4# / Sxe3#

We saw here a frame of presentation of themes, which is called Zagoruyko, and rises considerably the value of the problem.

Frame Zagoruyko : In at least three phases and in at least two (always the same) answers of black, the continuations of white are changed.

In Problem-39 the composer Manolescu presented a three-phased Zagoruyko with Grimshaw.

[This post in Greek language].

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