* #i1 * #i2 [2,3,4,6,7,8: @or_intror #H destruct ]
[2: elim (eq_nat_dec i1 i2) |1,3: elim (eq_nat_dec i1 i2) ] /2 width=1 by or_introl/
#Hni12 @or_intror #H destruct /2 width=1 by/
qed-.
* #i1 * #i2 [2,3,4,6,7,8: @or_intror #H destruct ]
[2: elim (eq_nat_dec i1 i2) |1,3: elim (eq_nat_dec i1 i2) ] /2 width=1 by or_introl/
#Hni12 @or_intror #H destruct /2 width=1 by/
qed-.