-lemma lift_iref_after_sn (f) (t:prototerm) (n:pnat):
- ā[fāš®āØnā©]t ā ā[f](šn.t).
-#f #t #n #p * #q #Hq #H0 destruct
-@(ex2_intro ā¦ (š±nāšŗāq))
+lemma lift_iref_sn (f) (t:prototerm) (n:pnat):
+ (šf@āØnā©.ā[ā*[n]f]t) ā ā[f](šn.t).
+#f #t #n #p * #q * #r #Hr #H1 #H2 destruct
+@(ex2_intro ā¦ (š±nāšŗār))