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

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

Def b == if b True else False fi

Thm* b:. b Prop

Thm* T:Type, E:(TTProp). (EquivRel x,y:T. E(x,y)) Prop

Def P Q == (P Q) & (P Q)

Thm* A,B:Prop. (A B) Prop

Def LangOver(Alph) == Alph*Prop

Thm* Alph:Type{i}. LangOver(Alph) Type{i'}

Def Trans x,y:T. E(x;y) == a,b,c:T. E(a;b) E(b;c) E(a;c)

Thm* T:Type, E:(TTProp). Trans x,y:T. E(x,y) Prop

Def Sym x,y:T. E(x;y) == a,b:T. E(a;b) E(b;a)

Thm* T:Type, E:(TTProp). Sym x,y:T. E(x,y) Prop

Def Refl(T;x,y.E(x;y)) == a:T. E(a;a)

Thm* T:Type, E:(TTProp). Refl(T;x,y.E(x,y)) Prop

Def P Q == Q P

Thm* A,B:Prop. (A B) Prop