Condition for a mathematical function to map some value to itself
In mathematics, a fixed-point theorem is a result saying that a functionF will have at least one fixed point (a point x for which F(x) = x), under some conditions on F that can be stated in general terms.[1]
^Brown, R. F., ed. (1988). Fixed Point Theory and Its Applications. American Mathematical Society. ISBN0-8218-5080-6.