TAK Function
A recursive function devised by I. Takeuchi in 1978. For integers x, y, and z, it is defined by t(x, y, z) = {y | for x<=y t(t(x - 1, y, z), t(y - 1, z, x), t(z - 1, x, y)) | otherwise auto right match This can be described more simply by t(x, y, z) = {y | if x<=y {z | if y<=z x | otherwise auto right match | otherwise auto right match Let T(x, y, z) be the number of times "otherwise" is called in the above function.