Question

_{what is a function?}

Answer 1

Let $A$ and $B$ be nonempty sets. A function f from $A$ to $B$ is an assignment of exactly one

element of $B$ to each element of $A$ .

We write $f (a) = b$ if $b$ is the unique element of $B$ assigned by the function $f$ to the element $a$ of $A.$

If $f$ is a function from $A$ to $B,$ we write $f : A → B.$