Mate Transference

In directmate problems, the idea of changed play can be separated into two categories. The more familiar one, changed mates, means that in two phases of play the same black defence leads to different white mating responses. The less usual type, known as mate transference, reverses the situation: in two phases, the same white mating move is induced by different black defences. In other words, a white mate that’s effective against one black defence is surprisingly ‘transferred’ to another black move.

The miniature 97 provides a neat example, showing changes between set and actual play. If Black were to begin, the main variations utilise the rook, 1…Rf5 (self-block) 2.Qh6 and 1…Rg5 (unguard) 2.Qxg5. A fine key, 1.Sd5!, creates two flight squares on h7 and h5 for the king, and threatens 2.Qf7. Black parries the threat by taking the flights, but White answers by giving the same mates as those seen in the set play, 1…Kh7 2.Qh6 and 1…Kh5 2.Qg5. That is, the two queen mates are transferred from the rook defences to the king moves.

Problem 98 illustrates mate transference along with focal play. The black rook in the diagram is ‘focusing’ on d5 and g4, the white knight’s mating squares. If Black moves the rook, the focus is lost and one of these squares will be left unprotected, yielding the set lines 1…R- on rank 2.Sd5, and 1…R- on file 2.Sxg4. However, the first move 1.Qa1! (waiting) pins the rook, and simultaneously unpins the black bishop. The latter now takes over as the thematic defender, and when it moves, the piece similarly loses the focus and enables the knight mates to recur: 1…Be2/d1 2.Sd5, and 1…B- else 2.Sxg4. There is by-play, 1…c4 2.Qxd4 and 1…d5 2.Qa6.

Notice that in the above examples, Black’s original defences (e.g. the rook moves in 98) are rendered illegal by the key. That these black moves are no longer playable makes the theme clearer, but mate transference can still occur when these defences remain legal. And if these particular black moves compel White to deliver new mates after the key, the Rukhlis theme is produced. Problem 99 presents such a scheme, a combination of mate transference and changed mates. The thematic try 1.Qxf7? (waiting) preserves two set variations, 1…dxe2 2.Sc2 and 1…fxe2 2.Sg2, in which White takes advantage of the simple unguards by Black’s pawns. Random moves by the black knight, 1…S~, permit 2.Qf4 but 1…Sd5! refutes. The key 1.Sc5! (waiting) grants two flights to Black, and the ensuing king moves provoke the knight mates we have just seen, 1…Kxd4 2.Sc2 and 1…Kf4 2.Sg2. But in addition, the set pawn defences are followed by a new pair of mates, 1…dxe2 2.Rxf3 and 1…fxe2 2.Rxd3. Now these pawn moves commit a different type of error, the opening of a white rook’s line to cover a flight. A further changed mate (not part of the Rukhlis scheme) pleasingly occurs in 1…S~ 2.Qxe4.

Problem 100 is an even more attractive Rukhlis. A Grimshaw interference is set on d4: 1…Rd4 2.Se3 and 1…Bd4 2.Sf4. The key 1.d4! cuts off the a4-rook and a7-bishop, but neither knight mate is threatened because of the pin formed on the second rank. White threatens 2.Qf3 instead, since the key-pawn has placed an extra guard on e5. When Black defends with the h2-rook, the knight is released and so allowed to mate again: 1…Rh4 2.Se3 and 1…Rh3 2.Sf4, i.e. the knight mates are transferred to these unpinning defences. Meanwhile, Black’s moves to d4 have changed their effects, from self-interferences to self-pins, and these errors are exploited accordingly with 1…Rxd4 2.Bc4 and 1…Bxd4 2.Rc5 – two pin-mates. Also, 1…Rxg2+ 2.Bxg2, 1…Sxg5 2.Qe5, 1…Qe6 2.Qxe6, and 1…Qxe7 2.Qc6.

The blending of mate transference and changed mates is further enhanced in the so-called Ideal Rukhlis. In Problem 101, the double-checks Sd4 and Se5 do not mate immediately because they interfere with lines controlled by the g1-bishop and g5-rook, respectively. Black allows these double-checks to work in the set play, after self-blocking on b6 and b5: 1…Bb6 2.Sd4, and 1…Sb5 2.Se5. Two more important set lines are 1…Qh2 2.Sxh2 and 1…Qd2+ Sxd2, making further use of the Q + S battery. White starts with 1.Qb2! (threat: 2.Qb7), which observes b6 and b5 but relinquishes the battery set-up. Now the knight mates are prevented for a different reason – direct guards by Black’s queen, hence the transferred mates when the queen tries to stop the threat by pinning White’s queen, 1…Qh2 2.Sd4, and 1…Qd2 2.Se5. The set defences 1…Bb6 and 1…Sb5 permit new mates, respectively 2.Qxb6 and 2.Qxb5, completing the Rukhlis. This problem achieves an Ideal Rukhlis because the variations 1…Qh2 2.Sd4 and 1…Qd2 2.Se5 feature not only mate transference, but changed mates as well, given the different set mates provided for these queen moves. (1…Rh2 2.Rc5, and 1…Bb4 2.Rxc7.)