Question

Uki

請問綠色框起來的是什麼意思

example.o
A,B: sets, |A|-|B|=n<∞
A function f : A → B is one to one
Proof
(F) Suppose 39, #az & fears = fiaz)
:
充分必要
if and only if it is onto. 7-1-4
3 | { bib = fca, for a EA & 979, 192}|≤n-2
=|f(A)| = h-1 < |B|
7 f is not
onto
Proof