Natural Deduction - Eliminating Negative Quantifiers

[Jordan Macdonald]

How are we supposed to eliminate negated quantifiers in Natural
Deduction? The summary tables don't seem to cover that.

[Woong Bin Kang]

You can try contradiction, but try a different approach ;)
Woongbin

How are we supposed to eliminate negated quantifiers in Natural Deduction?
The summary tables don't seem to cover that.

[Nancy Day]

Post by Jordan Macdonald
How are we supposed to eliminate negated quantifiers in Natural
Deduction? The summary tables don't seem to cover that.

Try to prove the opposite (i.e., the non-negated formula) in the
context of a proof by contradiction.

cheers, nancy
CS245 Winter 2009 Instructor