Def  Dec(P) == P  P

is mentioned by

Thm*  P:(AType). (x:A. Dec(P(x)))  (!{p:(A)| x:A. p(x)  P(x) })	[dec_pred_imp_bool_decider_exists]
Thm*  (x:T. Dec(E(x)))  (f:(T). x:T. f(x)  E(x))	[dec_pred_iff_some_boolfun]
Thm*  P XOR Q  (Q  P) & Dec(P)	[xor_vs_neg_n_dec]
Thm*  Dec(P)  Dec(P)	[dec_imp_dec_sq]
Thm*  Dec(P)  (b:. b  P)	[decbl_iff_some_bool]
Thm*  Q:Prop(given P). Dec(P)  (P  Dec(Q))  Dec(P & Q)	[decidable__cand]
Def  A Discrete == x,y:A. Dec(x = y)	[is_discrete]

In prior sections: core int 1 bool 1 rel 1 quot 1

Try larger context: DiscrMathExt IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html