When to use Conditional vs Conjunction

28 Views Asked by At

I'm studying proofs with Vellemans book "How to prove it".

I am having trouble understanding when I am supposed to use the "conjunction" vs "conditional".

My confusion is best illustrated with this example from the book:

Everyone has a roommate who dislikes everyone.

I translated this in the following way:

∀x ∃y ( R(x,y) ∧ ¬∃z L(y,z) )

Where R(x,y) means "x and y are roommates" and L(y,z) means "y likes z".

To me it made intuitive sense to use conjunction. Yet when I looked at the solution in the book, they used the conditional:

∀x ∃y ( R(x,y) → ¬∃z L(y,z) )

I know how their respective truth tables look like and I know that the conditional and the conjunction are not equivalent.

But I lack intuitive understanding of when to use which when translating statements like this one.