diff --git a/examples/example-exact-cover.spec b/examples/example-exact-cover.spec
index 1ba6168..63b3144 100644
--- a/examples/example-exact-cover.spec
+++ b/examples/example-exact-cover.spec
@@ -1,6 +1,3 @@
-# Auxiliary predicate to determine whether a variable is integer
-#axiom: forall X (is_int(X) <-> exists N X = N).
-
 # Perform the proofs under the assumption that n is a nonnegative integer input constant. n stands
 # for the total number of input sets
 input: n -> integer.