With depth 2, my engine returns 47x O-O castlings and 46x O-O-O castlings, (93 total) and I believe this is correct, but the website lists 91 castlings, so I checked by hand
Depth=1 (white to move): 48 moves with 2 castlings. So far I agree.
Now let's look at all illegal castlings (black to move) at depth=2,
I can only find 5.
If there were no illegal castlings, then the total number would be 2 + 48*2 = 98.
These are black's illegal castlings that I can find:
Code: Select all
O-O: 49 O-O-O: 49
after Bxa6: -1
after Nc6: -1
after Nxd7: -1
after Nxg6: -1
after Nxf7: -1
Am I missing something here?