Some definitions of interest.
assert	Def b == if b True else False fi
	Thm* b:. b  Prop
eq_rat	Def a =q b == a.numb.den=b.numa.den
	Thm* x,y:. x =q y
eq_int	Def i=j == if i=j true ; false fi
	Thm* i,j:. (i=j)
iff	Def P  Q == (P  Q) & (P  Q)
	Thm* A,B:Prop. (A  B)  Prop
qadd	Def a +q b == (a.numb.den+b.numa.den)/(a.denb.den)
	Thm* p,q:. p +q q
qmul	Def a *q b == (a.numb.num)/(a.denb.den)
	Thm* p,q:. p *q q
qdenom	Def q.den == 2of(q)
	Thm* q:. q.den
qnumer	Def q.num == 1of(q)
	Thm* q:. q.num
rat	Def  ==
	Thm*   Type

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