Changes

* [[Subtracting a rook Rook from a blocking pieceBlocking Piece|o^(o-2r)]].

At the first glance, [https://en.wikipedia.org/wiki/Arithmetic#Arithmetic_operations arithmetic operations], that is [https://en.wikipedia.org/wiki/Addition addition], [https://en.wikipedia.org/wiki/Subtraction subtraction], [https://en.wikipedia.org/wiki/Multiplication multiplication] and [https://en.wikipedia.org/wiki/Division_%28mathematics%29 division], doesn't make much sense with bitboards. Still, there are some [[Bit-Twiddling|bit-twiddling]] applications related to least significant one bit (LS1B), to [[Traversing Subsets of a Set|enumerate all subsets of a set]] or [[Subtracting a rook Rook from a blocking pieceBlocking Piece|sliding attack generation]]. Multiplication of certain pattern has some applications as well, most likely to calculate hash-indicies of [[Occupancy of any Line#Multiplication|masked occupancies]].

[https://en.wikipedia.org/wiki/Subtraction Subtraction] (like xor) might be used to implement the [[General Setwise Operations#RelativeComplement|relative complement]], of a [https://en.wikipedia.org/wiki/Subset subset] inside it's superset. As mentioned, subtraction may be useful in calculating [[Subtracting a rook Rook from a blocking pieceBlocking Piece|sliding attacks]].