0
1 else n
(n-1)! fi (recursive)
Thm* 
n:
. (n)! 
== {i:
| 0
i }
Thm* Type
j == if i=j true ; false fi
Thm* i,j:. i=j 
B == 
B < A
Thm* i,j:. ij Prop
A == A 
False
Thm* A:Prop. (A) Prop
| factorial |
Def (n)! == if n=0 1 else n(n-1)! fi (recursive)
Thm* |
| nat |
Def == {i:| 0i }
Thm* |
| eq_int |
Def i=j == if i=j true ; false fi
Thm* |
| le |
Def AB == B < A
Thm* |
| not |
Def A == A False
Thm* |
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