Some definitions of interest.
assert	Def  b == if b True else False fi
	Thm*  b:. b  Prop
lelt_int	Def  i  j < k == (ij)(j<k)
	Thm*  i,j,k:. i  j < k
band	Def  pq == if p q else false fi
	Thm*  p,q:. (pq)
iff	Def  P  Q == (P  Q) & (P  Q)
	Thm*  A,B:Prop. (A  B)  Prop
le_int	Def  ij == j<i
	Thm*  i,j:. (ij)
lelt	Def  i  j < k == ij & j<k
lt_int	Def  i<j == if i<j true ; false fi
	Thm*  i,j:. (i<j)

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