P
A:Prop. Dec(A) 
PropxL.P(x) == (letrec list_all L = (Case of L; nil 
True ; h.t P(h) & list_all(t)) ) (L)T:Type, P:(T
Prop), L:T List. xL.P(x) TypeT:Type, P:(TType). xnil.P(x) TypeA == A 
FalseA:Prop. (A) Prop| Who Cites decidable? | |
| decidable | Def Dec(P) == P P |
| Thm* A:Prop. Dec(A) Prop | |
| list_all | Def xL.P(x) == (letrec list_all L = (Case of L; nil True ; h.t P(h) & list_all(t)) ) (L) |
| Thm* T:Type, P:(TProp), L:T List. xL.P(x) Type | |
| Thm* T:Type, P:(TType). xnil.P(x) Type | |
| not | Def A == A False |
| Thm* A:Prop. (A) Prop | |
| letrec_body | Def = b == b |
| letrec_arg | Def x b(x) (x) == b(x) |
| letrec | Def (letrec f b(f)) == b((letrec f b(f)) ) (recursive) |
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