In mathematics, a multivalued function is a total relation; i.e. every input is associated with one or more outputs. Strictly speaking, a "well-defined" function associates one, and only one, output to any particular input. The term "multivalued function" is, technically, a logical contradiction, "true" functions are monovalued.

The above diagram does not represent a "true" function; because, the element 3, in X, is associated with two elements b and c, in Y.

See also:

• partial function