If I'm not mistaken... This is just Aristotelian logic. Euclid based his entire book on If, And, Then statements.
The first two statements are assumptions, and the third statement is the conclusion which, as Aristotle put it, "follows of necessity" from the assumptions.
One could assume that all students love math and that Harry was a student. One may dispute these assumptions, but there's no disputing that from these assumptions it necessarily follows that Harry loves math.
Pictures aren't really my forte...