reductions (in computer science algorithms)

show that transformation IS a reduction, that is

the graph G has a clique of size k iff G' has a vertex cover of size |V| - k

if and only if: -- this is EQUALITY

if A then B
if B then A

if not A then not B
if not B then not A

hmmmm.......

if:

if A then B
if not B then not A (that's all you know)

A B if

0 0 1

0 1 0

1 0 0

1 1 1