theorem ext2_trans: ∀R. Transitive … R → Transitive … (ext2 R).
#R #HR #I1 #I #H elim H -I1 -I
[ #I1 #J #H >(ext2_inv_unit_sn … H) -J /2 width=1 by ext2_unit/
theorem ext2_trans: ∀R. Transitive … R → Transitive … (ext2 R).
#R #HR #I1 #I #H elim H -I1 -I
[ #I1 #J #H >(ext2_inv_unit_sn … H) -J /2 width=1 by ext2_unit/