Involution (mathematics)

In mathematics, an involution, involutory function, or self-inverse function is a function f that is its own inverse, f(f(x)) = x for all x in the domain of f. Equivalently, applying f twice produces the original value. The term anti-involution refers to involutions based on antihomomorphisms (see below) f(xy) = f(y) f(x) such that xy = f(f(xy)) = f( f(y) f(x) ) = f(f(x)) f(f(y)) = xy.

Involution (mathematics)

In mathematics, an involution, involutory function, or self-inverse function is a function f that is its own inverse, f(f(x)) = x for all x in the domain of f. Equivalently, applying f twice produces the original value. The term anti-involution refers to involutions based on antihomomorphisms (see below) f(xy) = f(y) f(x) such that xy = f(f(xy)) = f( f(y) f(x) ) = f(f(x)) f(f(y)) = xy.