Single-valued function

A single-valued function is an emphatic term for a mathematical function in the usual sense. That is, each element of the function's domain maps to a single, well-defined element of its range. This contrasts with a general binary relation, which can be viewed as being a multi-valued function. A single-valued function is One-to-One if and only if it is also single-rooted. For example : f(x) = x+3 (each element in domain has not more than one image in range set).