Negating a statement State in words the negation of the following sentence: For every martian M, if M is green, then M is tall and ticklish. I got the right answer to this, give or take a few words, but this is a question of form more than anything. After converting this statement to symbols and negating everything, I come up with: $\exists M(P \wedge (\neg \text{Tall } \vee \neg\text{ Ticklish})$ and so in word format that would be: > There exists a martian such that it is green and not tall or not ticklish. However the really correct answer is: > There is a martian M such that M is green but M is not tall or M is not ticklish. The difference between these two is a 'but' and an 'and'. Does this mean anything mathematically? Is my version correct?

Your answer is "really correct". It is perhaps more usual in English to use "but" rather than "and" in a sentence as the one in your example. Formally (i.e., mathematically), there is no difference.