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in the late 90s an American teen programmer and inventor of the [[Reverse Bitboards]] when he was a 16 year old schoolboy. In 2000, while introducing his ''Hyperbola Project'', he explained the <span style="background-color: [[Subtracting a Rook from a Blocking Piece#c0c0c0;">oxoro2r|x XOR (x - 2)</span> ]] [[Bit-Twiddling|bit-twiddling]] trick as the basic idea of Reverse Bitboards, essentially [[Subtracting a Rook from a Blocking Piece|subtracting a rook from a blocking piece]], where the changed bits masked on a line remain the sliding [[On an empty Board#RayAttacks|ray-attacks]] in [[On an empty Board#PositiveRays|positive]] [[Rays#RayDirections|ray-directions]]. His idea to keep a [[Flipping Mirroring and Rotating#Rotationby180degrees|reversed or 180 degree rotated]] [[Occupancy|occupancy]] to apply the same trick for [[On an empty Board#NegativeRays|negative]] ray-directions to yield reversed attack bitboards, either requiring bitboard reversal or disjoint [[Bitboard Serialization|serialization]] with reversion in the square centric world by [[General Setwise Operations#ExclusiveOr|xor]] 63, turned out to be not that successful as the young author initially thought and claimed. However, [[Hyperbola Quintessence]], where fast vertical byteswap flipping is used on the fly to reverse [[Diagonals|diagonals]] and [[Files|files]], is somehow the resurrection of Ryan's ideas, vastly improved by [[Aleks Peshkov|Aleks Peshkov's]] xor wizardry.