Recurrence of the 2 nd move by the black King on the 1 st move in h#2
By Abdelaziz Onkoud
StrateGems N°83 , July September 2018
Let's consider the following idea in a 2-solution helpmate in two moves: The 2 nd move by k in one solution reappears on the 1 st move of the second solution.
We are going to study the reasons preventing Black or White from copying the same play on the 1 st moves, in the solution where the k plays on B2. 1.X A 2.k(a) 1.k(a) ... 2.... The inversion may fail in two different ways:
1.k(a) ... 2.X?? (X does not work, because the k prevents X or A which is not possible, or A prevents X.)
1.k(a) A?? 2... (A does not work, because X is not possible or A is not possible or A attacks the k or A prevents X.)
Here are some of the reasons:
- 1- Because some white Pawns are blocked (A is not possible)
- 2- Because White will check the k (X does not work because A prevents X and A attacks the k.)
- 3- Because the lines of white pieces are closed (A is not possible)
- 4- Because White captures black units that are necessary for the solution (A prevents X)
- 5- Because the k closes the lines of black pieces (X does not work, because the k prevents X)
- 6- Because the white pieces need sacrifices of black pieces (A is not possible)
- 7- Because the white pieces must be unpinned (A is not possible).
At the Marianka festival in August 2016, the tourney theme required that black moves played on B1 in one solution be repeated on B2 in another solution, according to the following scheme: Idea scheme: 1..... 2.a ... 1..... 2.b ... 1.a 2...... 1.b 2...... I already had N°2 in stock and also an article in the planning stage.
It was an opportunity for me to compose examples with the different, above-mentioned, reasons. I was especially interested in the motives concerning the black King. I excluded the black move inversions (as per rules of the Marianka tourney). If it was allowed, the idea would lose its interest in my opinion. New moves were needed.
My thanks to Michel Caillaud for the perspective presented as I was finishing the article and to Eric Huber for his translation
