Fixes infinite loop

src/prover/constraints.rs

@@ -1,11 +1,9 @@
 use std::fmt::Display;
 
 use litemap::LiteMap;
-use winnow::Str;
 
 use crate::ast::Predicate;
 use crate::ast::Variable;
-use crate::prover::constraints;
 
 #[derive(Clone, Debug)]
 pub struct Constraints
@@ -33,6 +31,10 @@ impl Constraints
     {
         if let Some(other_predicate) = self.set.get(variable)
         {
+            if predicate == other_predicate
+            {
+                return true;
+            }
             // If variable is already contrained, we need to check if both contraints are
             // contradictory