I wonder if there is a program that has commands like perftpass when the program simply counts number of passed pawns in the leaf positions of games of n plies.
for example in the opening position 1.a4 b5 2.b4 bxa4 should be count as 1 when you calculate perftpass(4) because black has one passed pawn(pawn a4).
It means that in the opening position
perftpass(4)>=1 inspite of the fact that it is sum of numbers that almost all of them are 0.
1.a4 b5 2.b4 bxa4 3.b5 a5 4.bxa6 is calculated as 2 in perft 7(white has a6 and black has a4 so there are 2 passed pawns in the board)
Uri