Some definitions of interest.
reduce_factorization	Def  reduce_factorization(f; j)(i) == if i=j f(i)-1 else f(i) fi
	Thm*  a,b:, f:({a..b}), j:{a..b}. Thm*  0<f(j)  reduce_factorization(f; j)  {a..b}
eq_int	Def  i=j == if i=j true ; false fi
	Thm*  i,j:. (i=j)
int_seg	Def  {i..j} == {k:| i  k < j }
	Thm*  m,n:. {m..n}  Type
nat	Def   == {i:| 0i }
	Thm*    Type
le	Def  AB == B<A
	Thm*  i,j:. (ij)  Prop

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