Some definitions of interest.
rem_nrel	Def Rem(a;n;r) == q:. Div(a;n;q) & qn+r = a
	Thm* a:, n:, r:. Rem(a;n;r)  Prop
div_nrel	Def Div(a;n;q) == nq  a < n(q+1)
	Thm* a:, n:, q:. Div(a;n;q)  Prop
nat	Def  == {i:| 0i }
	Thm*   Type
nat_plus	Def  == {i:| 0<i }
	Thm*   Type

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