CIS 1910 Lecture Notes - Lecture 14: Luiza, Contraposition, Bijection

• School: University of Guelph
• Department: Computing and Information Science
• Course: CIS 1910
• Professor: Luiza Antonie

Document Summary

One-to-one or injective functions: a function f : x y is one-to-one or injective if x1 = x2 = f (x1) = f (x2) . That is, f maps different elements in x to different elements in y a b c. De ne f : z z, f (x) = 2 x + 5. By contrapositive: f (x1) = f (x2) = x1 = x2. 2 x1 + 5 = 2 x2 + 5. 2 x1 = 2 x2 x1 = x2. Onto or surjective functions: a function f : x y is onto or surjective if the range of f is equal to the target y . That is, for every y y , there is an x x such that f (x) = y a b c d. De ne f : z z, f (x) = x2.