Sunday, March 30, 2008

Three-movers

We call three-movers the problems which have three-move-solution.

In orthodox three-movers the series of moves is W – B – W – B – W (white plays the key – black plays defense – white continues attack – black continues defense – white gives mate). Another way to denote moves : W1 first white move, B1 first black move, W2 second white move, B2 second black move, etc..

In heterodox helpmate three-movers the series of moves is B – W – B – W – B – W (in helpmates black plays first).

In heterodox selfmate three-movers the series of moves is W – B – W – B – W – B.

If it is not accompanied by any characteristic, the expression three-mover means orthodox three-mover.

The problem of the engineer Lyris Basil seems to be quite simple, since the black king is already pushed in the corner h8 and with a checking the mate is done. For example, if the bishop leaves g6, the knight with move Sg6 gives check and maybe mate.
 (Problem 12) Lyris D. Basil, "To Skaki", December 1943 White plays and mates in 3 moves #3 (5+2) [7k/7P/6BK/8/7S/8/6R1/6r1]

This solution teaches us that, looking for it, we must use all the area of the chessboard.
Try {1.Bh5? [2.Sg6#] Rxg2!}
Try {1.Rf2? Rf1! (We have tried to move to the left Rg2 to square f2 in order to threaten with 2.Rf8 mate in the eighth row, and the black has replied 1...Rf1 stopping this threat. If now we move the bishop to threat mate with the knight, let us say 2.Be4, the black replies with switchback of the rook, 2...Rg1!, and mate cannot be done in the third move. The other tries have similar continuation)}.
Try {1.Re2? Re1!}
Try {1.Rd2? Rd1!}
Try {1.Rc2? Rc1!}
Try {1.Rb2? Rb1!}

Key 1.Ra2! Ra1 (and here the question arises : in what aspect does this move differ from the five previous moves?)
2.Βb1 (It traps the black rook)
2...Rx~ (The symbol x means captures a piece. The symbol ~ means any piece, any square. The trapped R in the corner a1 may capture any piece it chooses, Ra2 or Bb1, but it cannot stop mate at the opposite corner of the board)
3.Sg6#

The three-movers can have complex themes, (Roman, Plachutta, etc), which will be presented in next posts.

[This post in Greek language].