Remove custom simplify for z3 expression

dtree_synth.py

@@ -54,12 +54,12 @@ def synth_dtree(learner: LearnerBase, teacher: TeacherBase, num_max_iterations:
             continue
         elif result == z3.unsat:
             print("we are done!")
-            z3_expr = tacticSimplify(z3.simplify(candidate, arith_lhs=True))
+            z3_expr = z3.simplify(candidate, arith_lhs=True)
             ret = {"k": k, "formula": z3_expr.sexpr(), "smtlib": z3_expr.serialize()}
             return True, ret, (teacher_time,learner_time)
         else:
             assert result == z3.unknown
-            z3_expr = tacticSimplify(z3.simplify(candidate, arith_lhs=True))
+            z3_expr = z3.simplify(candidate, arith_lhs=True)
             ret = {
                 "reason": f"Reason Unknown {teacher.reason_unknown()}",
                 "k": k, "formula": z3_expr.sexpr(), "smtlib": z3_expr.serialize()