| | Some definitions of interest. |
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| deq | Def EqDecider(T) == eq:T T    x,y:T. x = y  (eq(x,y)) |
| | | Thm* T:Type. EqDecider(T) Type |
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| assert | Def b == if b True else False fi |
| | | Thm* b: . b Prop |
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| iff | Def P  Q == (P  Q) & (P  Q) |
| | | Thm* A,B:Prop. (A  B) Prop |
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| proddeq | Def proddeq(a;b)(p,q) == (1of(a)(1of(p),1of(q))) (1of(b)(2of(p),2of(q))) |
| | | Thm* A,B:Type, a:EqDecider(A), b:EqDecider(B). proddeq(a;b) A B A B   |