Def as @ bs == Case of as; nil bs ; a.as' a.(as' @ bs) (recursive)

Thm* T:Type, as,bs:T*. (as @ bs) T*

Def {i..j} == {k:| i k < j }

Thm* m,n:. {m..n} Type

Def ||as|| == Case of as; nil 0 ; a.as' ||as'||+1 (recursive)

Thm* A:Type, l:A*. ||l||

Thm* ||nil||

Def == {i:| 0 < i }

Thm* Type

Def AB == B < A

Thm* i,j:. ij Prop

Def A == A False

Thm* A:Prop. (A) Prop