Original—A → B

To be a Jedi, one must be able to use the Force.

Contrapositive = equivalent

/B → /A

If you can't use the Force, you're not a Jedi.

Inverse ✗ not equiv.

/A → /B

If you're not a Jedi, you can't use the Force.

Negation severs the link

A and /B

One can be a Jedi without being able to use the Force