Retroanalyse im Schach

# Bernd Gräfrath

Aufgaben und Lösungen

3 -

Korrektur von Nr. 13162 in Skakbladet, Juni 2002, S. 19

10+9. Weiß hat beide Springer vorgegeben und darf noch rochieren. a) Was war der letzte Zug? b) Was war der erste Zug?

[8/p1ppp1pp/1p3b2/k4P2/5P2/4P1P1/PP2PP2/4K2R]

Lösung

The bishop at f6 is a promoted pawn. This can only have happened at g1. (After c1L, the bishop would have forced the white king to move after a check at d2.) The move g2-g3 occured only after the promoted bishop returned via h2, g3 and h4. So the black pawn f7 went to g1 via the g-file and the h-file, capturing three white pieces on the way. The last missing white piece is the white bishop f1, which could only get out after g2-g3 had been played. The white pawn e3 came from d2, f4 came from h2, and f5 came from c2, all together capturing six black pieces. (The other missing black piece was the bishop f8, which was captured on its original square.)

All captures of black pieces must have occured before White played g2-g3, because they were needed as waiting moves during the advance of the pawn f7 and the return of the bishop g1. (Otherwise, White would have lost his right to castle.)

Black's last move cannot have been the capture of White's white-squared bishop, because no black piece is standing on an appropriate white square. So White does not have a legal last move, if there were further moves after g2-g3. (All tempo moves had been used up before.) Therefore, g2-g3 must actually have been White's last move, and it turns out that the white bishop f1 must have been captured before by a black knight on its original square. So the very last move was made by Black, playing Lf6-e5.

White's very first move wasn't with a knight, because he didn't have any. It also wasn't with a pawn, because all of his pawns' first moves had to be captures, except for g2, which however, could only move very much later. So his first move was with a rook; and since the rook at h1 hasn't moved yet, White's first move was Ta1-b1.

Interesting things began to happen after White captured a black knight (or the black queen) at e3, letting out his queenside pieces.

This retrograde analysis may be clearer if a position is given which might have occured 7 moves ago.

[8/p1ppp1pp/1p3b2/k4r2/4rq2/3bP1PQ/PPP1PPP1/4K2R]

Then roughly the following happened: 1. Dh2 h3 2. Dg1 h2 3. cxd3 hxg1L 4. dxe4 Lh2 5. gxf4 Lg3 6. exf5 Lh4 7. g3 Le5.