I have attached a question that I am having trouble with. Thanks to anyone who can help.DOC1.DOC
Hello Mel
Here is the problem.
Suppose and are nonempty sets and is a function. Let and be subsets of . Prove that
We do this by showing that and
So, for the first part:
Suppose . Then for some , , and .
or [Note: throughout this proof 'or' means 'inclusive or'. So or means or or both.
or
or
So
(1)
For the second part:
Suppose
Then or
Then for some , and or
So
(2)
So, from (1) and (2):
Grandad