## Saturday, December 25, 2010

### The twelve puzzles of Xmas

Turco, 1983

Mate in one

Anonymous said...

Merry Xmas. I think the answer is Nxc2# on the basis that knights and rooks can't lose a move therefore it's black to play. Or am I missing something?

PG

ejh said...

That's right, if a little truncated...care to elaborate?

Anonymous said...

Yes, it is Nxc2#. Let me try to put down some basic reasoning.

The knight on a1 coming from b8 corresponds with the knight on h8 from g1, taking up the same number of ply.
The knight on d1 ex-b1 corresponds to the knight on e8 ex-g8, taking up the same number of ply.
The rooks on b1 and g8 both take one ply to get there.
The black king on d8 represents an odd one ply. Therefore it is Black to move and the solution is 1. ... Nxc2#.

Anonymous said...

It's a retrograde problem. Any sequence of moves leading to that position would result in it being black to move, as to reach the resulting position white would have had to make one more move than black.

PG

ejh said...

Yes, well done: although it would normally be White to move in problem, retro-analysis demonstrates that it cannot actually be White's move.

The problem was (apparently) originally published in diagrammes and my source for it was Angela Und Otto Janko: Retrograde Analysis Corner, A Retro Glossary, Mate in One.

Martin S. said...

I'm sneaking round the back of ejh's puzzles to try and apply the aesthetic "elements" given by Levitt and Friedgood in their Secrets of Spectacular Chess 2nd ed. (2008). viz Paradox, Depth, Geometry, and Flow. To keep this comment short I'll give their definition of just one here, and the others on the puzzle/posts following.
"Geometry. Patterns, repetitions, echoes, ....the response might be 'Oh, what a pretty pattern!'...any striking pattern or special feature could be included..."

I reckon the Turco scores for Geometry - just look at that mirror position! Maybe Paradox as well: with two mates on offer "how can this be possible?" as L & F put it. But "Deep" or "Flowing"? Nah.