View Single Post
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.
Phys.Org News Partner Science news on
Wildfires and other burns play bigger role in climate change, professor finds
SR Labs research to expose BadUSB next week in Vegas
New study advances 'DNA revolution,' tells butterflies' evolutionary history