The Retrograde Analysis Corner
Series-movers ask for one side to play a long series of consecutive
moves. In series-mates, White plays the series and try to mate
Black at the end of the series. In series-helpmates, Black
plays the series and try to reach a final position where White may mate
in one. In series-selfmates, White plays the series and try
to reach a final position where Black must mate him in one.
During the series, it is not allowed to walk into check, or to check
the opponent before the last move of the series, when he can answer
Consequent series-movers are series-movers where, at every
moment during the series, the intermediary position must be legal as
if we were in an orthodox game. The previous rules about walking into
check still apply, but additionally it is not possible to enter positions
with no retro-analytically "legal past". For retro-analytical purposes,
all intermediary positions are evaluated independently.
Ded. G. Yacoubian
5+10. shc#15 (Consequent Series-Helpmate
in 15 moves)
The try 1. Ra3 2. Rxb3?? 3. Rb5 4. Bb4 5-7. Kc4 8. Rc5 9. b5 b3# fails
because Wh. has no last move after 2. Rxb3.
The solution is to first capture the wh. Pg2 so that the White King
has -1. Kg2-h1 as a possible last move. 1. Rf8 2. Rf2 3. Rxg2!! 4. Rf2
5. Rf8 6. Ra8 and we go on as in the try.
Rex Multiplex 15-16, 1985
5+3. shc#8 (Consequent Series-Helpmate
in 8 moves)
After 1. Kf8 2. Ke8 we reach a position where, if it was the starting
point of a problem, Bl. could castle according to the
usual conventions for castling rights.
In consequent series-movers, the intermediary positions are evaluated
independently, so that we may go on as if we were in the starting position
and play 3. O-O!!. The fact that we have just moved
the bl. King from g8 is explicitly disregarded in consequent series-movers.
Now 4. Rxa8 5. Kf8 6. Ke8 7. O-O-O!! is legal according to the consequent
series-mover logic. We conclude with 8. Rd7 Ra8#.