Easy# One-to-one Correspondence, Bijection

ABSALG-JE4SEK

A function $f:S\rightarrow T$ that is **both** one-to-one and onto is called a *one-to-one correspondence* (or *bijective function* or *bijection*). For some reason *onto* got dropped from the terminology *one-to-one correspondence*, so you should remember that *onto* is part of it nonetheless. You can think of a *one-to-one correspondence* as being a function $f$ matches every element $t\in T$ to just one $s\in S$.

Which of the following functions are **NOT** one-to-one correspondences?

By ${\mathbb C}$ we mean the complex numbers, and $i=\sqrt{-1}$.

Select **ALL** that apply.