Solution
C. Wiedenhoff 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#.
