| == (letrec l L = (Case of L; nil 
0 ; h.t 1+l(t)) ) 
T:Type. || 
(T List)
T:Type. || (T List)
== {i:| 0
i } TypeB == 
B < Ai,j:. (ij) PropA == A 
FalseA:Prop. (A) Prop| Who Cites list length? | |
| 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) | |
| nat | Def == {i:| 0i } |
| Thm* Type | |
| 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) |
| le | Def AB == B < A |
| Thm* i,j:. (ij) Prop | |
| not | Def A == A False |
| Thm* A:Prop. (A) Prop |
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