# Are the following set of ordered pairs function? If so,examine whether the mapping is injective or subjective $\;\{(a,b)\;:\;a\;$ is a person,$b\;$ is an ancestor of $a\}$

Note: This is part 2 of a 2 part question, split as 2 separate questions here.

Toolbox:
• A function $f:A \to B$ is injective. if $f(x_1)=f(x) \Rightarrow x_1=x_2$ for $x_1,x_2 \in A$
• A function $f:A \to B$ is surjective if for every element  $y \in B$ then exists an element x in A such that f(x)=y
{(a,b):a is a person, b is an ancestor of a}
Since the ordered map (a,b) does not map 'a' - a person to a living person
This is not a function

edited Apr 5, 2013