Brian Tomson, series helpmate in 26

We’ve written previously here about the Irish player and problemist Brian Tomson. He played in the Glorney Cup, Armstrong Cup (for T.C.D.), finished equal 4th in the Irish championship in 1965, and represented Ireland in the Student Olympiad in 1967, before emigrating to Australia in 1968. He died in Newcastle, Australia in July 20, 1986, thirty years ago today.

Here is another of his problems:

Tomson, Series helpmate in 26
Series helpmate in 26 (Tomson, 1981)

For those unfamiliar with this problem type, it’s a helpmate, so White and Black are working together to help White mate Black. It’s also a “series” problem: Black will play 26 consecutive moves, with White’s pieces remaining static. All Black moves must be legal, and all but the last must leave a position where Black could legally move next, i.e., there can be no checks in Black’s first 25 moves. Then White plays one move to checkmate Black.

The length of the solution may make the problem seem daunting, but in fact Black has so few choices that it’s quite accessible. Answer in a few days.

[Update, June 25, 2016: see comment for solution.]

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One Response to Brian Tomson, series helpmate in 26

  1. Sean Coffey says:

    As with most series problems, the first step is to identify the eventual mate, and only then to try to find how to achieve it. Here the obvious candidate is for the black king to make its way to a2, when White can play Ra7 mate.

    Some initial attempts illustrate the difficulty: if … cxd4, Ba7, Bc5, Be7, Kf7, Ke6, Black has made some progress, but what next? d5 is not available, d4 is also currently blocked (and can’t be unblocked since … d3+ isn’t allowed in the middle of the sequence), and d6 leads nowhere. On the other hand … c4, Ba7, Bc5, Be7, Ke6, Ke5, Kd4 is also a dead end, since c4 is blocked. Somehow Black needs to eliminate the knight and bring the black bishop to e7 while keeping c4 and d4 clear.

    But the bishop can go the long way around! With this idea the solution falls into place. After Ba7-b6-a5-b4-a3-c1-d2-e1-h4-g5-h6-f8-d6-e5xd4 (eliminating the knight, 15 moves) -e5-d6-e7 (shielding the king, 3 moves), Kf7-e6-e5-d4-c4-b4-a3-a2 (8 moves), Black has played 26 moves, and White replies Ra7 mate.

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