Prolog error: full stop in the -body section? I can not override, / 2

Question

I just started to study prologue. I compiled the file with SWI-Prolog, but received the error message: Prolog error: full stop in the -body section?

My file:

loves( vincent , mia ) . loves( marsellus , mia ) . jealous(X,Y) := loves(X,Z) , loves(Y,Z) . 

Answer 1

Stupid, I realized that this should be: -, not: =.