]
qed.
-lemma fsubst_eq_repl (t1) (t2) (u1) (u2) (p):
- t1 ⇔ t2 → u1 ⇔ u2 → t1[⋔p←u1] ⇔ t2[⋔p←u2].
-#t1 #t2 #u1 #u2 #p * #H1t #H2t * #H1u #H2u
+lemma fsubst_eq_repl (t1) (t2) (u1) (u2) (p1) (p2):
+ t1 ⇔ t2 → p1 = p2 → u1 ⇔ u2 → t1[⋔p1←u1] ⇔ t2[⋔p2←u2].
+#t1 #t2 #u1 #u2 #p1 #p2 * #H1t #H2t #Hp * #H1u #H2u
/3 width=5 by conj, subset_inclusion_fsubst_bi/
qed.