Involution (mathematics)

In mathematics, an involution, or an involutory function, is a function f that is its own inverse, In mathematics, an involution, or an involutory function, is a function f that is its own inverse, for all x in the domain of f. The term anti-involution refers to involutions based on antihomomorphisms (see below the section on Quaternion algebra, groups, semigroups)