x,y:T. Dec(x = y)T:Type{i}. Discrete{T} 
Type{i'}
PA:Prop. Dec(A) Prop
| == (letrec l L = (Case of L; nil 
0 ; h.t 1+l(t)) ) T:Type. || (T List)
T:Type. || (T List)
A == A 
FalseA:Prop. (A) Prop| Who Cites discrete? | |
| discrete | Def Discrete{T} == x,y:T. Dec(x = y) |
| Thm* T:Type{i}. Discrete{T} Type{i'} | |
| decidable | Def Dec(P) == P P |
| Thm* A:Prop. Dec(A) Prop | |
| list_length | Def || == (letrec l L = (Case of L; nil 0 ; h.t 1+l(t)) ) |
| Thm* T:Type. || (T List) | |
| Thm* T:Type. || (T List) | |
| 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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