Some definitions of interest.
ge	Def ij == ji
	Thm* i,j:. (ij)  Prop
gt	Def i>j == j<i
	Thm* i,j:. (i>j)  Prop
nat	Def  == {i:| 0i }
	Thm*   Type
le	Def AB == B<A
	Thm* i,j:. (ij)  Prop
nat_plus	Def  == {i:| 0<i }
	Thm*   Type

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