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 Problem of the Week

368. Norman Macleod
Chess World 1950
Mate in 2

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9 Nov. 2017 – The le Grand theme – Part 2

In this follow-up column on the le Grand theme, we look at some ways by which the idea could be elaborated. Recall that the theme involves a type of a reciprocal change between try and actual play, based on this pattern: a try threatens mate A and the defence x permits mate B, but the key threatens mate B instead and the same defence x allows mate A. In the first example, the scheme is augmented by another thematic try to bring about a three-fold change of mates. The second problem illustrates how the le Grand could be effectively transposed to a three-mover.

Peter Hoffman
Die Schwalbe 1989
3rd Prize
Mate in 2

The black king has a flight-move to e4 and it is the thematic defence. The first try 1.Bf4? guards d6 to threaten 2.Sxf6 [A], and since the try-bishop has also covered e3, 1…Ke4 [x] enables 2.Qc4 [B], but 1…f5! refutes. The second try 1.Be2? controls c4 to threaten 2.Qc4 [B], and now 1…Ke4 [x] permits 2.Qd3 [C], thanks to the extra guard on d3 by the try-bishop; however, Black escapes with 1…Ke6! Finally, the key 1.Bd7! attacks c6 to threaten 2.Qd3 [C], and 1…Ke4 [x] leads to another changed mate, 2.Sxf6 [A]. Instead of the reciprocal pattern found in the standard le Grand, this problem shows an extended version with a circular relationship between the moves: first try? (threat 2.A), 1…x 2.B; second try? (threat 2.B), 1…x 2.C; key! (threat 2.C), 1…x 2.A. This is a cyclic le Grand, impressively achieved in miniature form.

Though nominally a two-move scheme, the le Grand could also occur in three-movers. One method of transferring the idea, exemplified by the problem below, dispenses with the thematic try but shifts the main play to the second and third moves. Thus White has two second-move continuations (corresponding to the try and the key of a two-mover), each followed by a threat [3.A or B] and a variation mate [3.B or A], and these third moves are reversed with respect to the same second-move defence [2…x].

Waldemar Tura
Martin 1995
2nd Prize
Mate in 3

The key 1.Ra4! carries the threat of 2.Bc4+ Kc6 3.Sd8, against which Black has only two defences, 1…Qb4 and 1…Qc3. Either black move means White could push the f2-pawn and threaten a queen mate on e4 or e5, since 2…Qh4+ has been ruled out. Now 1…Qb4 forces 2.f3 with the threat of 3.Qe4 [A], and 2…d3 [x] opens not only a defensive line for the black queen but also an offensive line for the b2-bishop: 3.Qe5 [B]. (2…Se6 3.Qxe6.) Not 2.f4? here because of 2…Qxb5! If 1…Qc3 then 2.f4 threatens 3.Qe5 [B], and the same defence 2…d3 [x] opens both a defensive line for the black queen and an offensive line for the white rook: 3.Qe4 [A]. (2…Sd7, etc. 3.Qe6.) This time, not 2.f3? because of 2…Qd3/Qc2! The double paradox of 2…d3 disabling/enabling 3.Qe4/Qe5 is apparent here, along with the beautifully matched line play.

8 Oct. 2017 – The le Grand theme – Part 1
3 Sep. 2017 – Weekly Problems and Walkabout archives
13 Aug. 2017 – Kamikaze Chess