MATH 092 Lecture 7: FUNCTIONS AND MAPPINGS
1 Aug 2016
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Document Summary
A junction is a relation j such that each domain element x is paired with exactly one range element y. ej and - ej =} y = z. The y which is thus uniquely determined by f and x is designated f(x): y = f(x) ~ ef. One tends to think of a function as being active and a relation which is not a function as being passive. A function f acts on an element x in its domain to givef(x). We take x and apply fto it; indeed we often call a function an operator. We often define a function f by specifying its value f(x) for each x in its domain, and in this connection a stopped arrow notation is used to indicate the pairing. Thus x 1-+ x2 is the function assigning to each number x its square x2.
