Arrival effect
The effect induced by the arrival of a certain piece to its destination square or line. In other words, all the differences between a position with this piece on the board (after the move) and position without it,just before the move was finished (i.e. the piece was still "in the air").
Helpmate Analyzer only considers the positive effects of moves.
See also: Departure effect.
Feather, Christopher John
Moultings 2, 1991
h#2 2.1... (6+7)
1.Qh8
Bd3
2.e5
Rd5#
1.Qg8
Be2
2.f5
Re5#
B1 - Direct unpin, Unguard of mating line,
W1 - Line opening for guarding,
B2 - Unguard of mating square.
Arrival effects:
B1 - Hideaway,
W1 - Interference / anticipatory unguard of mating square,
W2 - Check.