Some definitions of interest.
nat_plus	Def  == {i:| 0<i }
	Thm*   Type
qdenom	Def q.den == 2of(q)
	Thm* q:. q.den
qnum	Def p/q == <p,q>
	Thm* n:, d:. n/d
qnumer	Def q.num == 1of(q)
	Thm* q:. q.num

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