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torquerotates is offline
Mar9-11, 12:11 AM
P: 204
So if I want to prove. A=>B for all x.

Does the following work?

Suppose for contradiction, B is not true for all x, that is, there exists at least one x such that B is not true. In particular, assume that B is true for x=c and B isn't true for all other x. If I arrive at a contradiction, then A must imply B.

So does it work if I pick a single value of x such that B is true and let B not be true for all other values? This is a little confusing because the negation simply specifies the case for at least one x such that B isn't true. There could be more than one x such that B isn't true.
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