Hey I was reading Susanna Discrete book and I came across her definition of One-to-One function:
Let F be a function from a set X to a set Y. F is one-to-one (or injective) if, and only if, for all elements x1 and x2 in X,
if F(x1 ) = F(x2 ),then x1 = x2 ,
or, equivalently, if x1 ≠...