Some definitions of interest.
iff	Def P  Q == (P  Q) & (P  Q)
	Thm* A,B:Prop. (A  B)  Prop
rel_inverse	Def R^-1(x,y) == y R x
	Thm* T1,T2:Type, R:(T1T2Prop). R^-1  T2T1Prop
rel_star	Def (R^*)(x,y) == n:. x R^n y
	Thm* T:Type, R:(TTProp). (R^*)  TTProp

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