At: bool listify 1 1 2 1 2
1. T: Type
2. f: T


3. n: 
4. f1:
n
T
5. Bij(
n; T; f1)
6.
k:
. k
n 
(
fL:T*. (
t:T. mem_f(T;t;fL) 
f(t)) & (
i:
k. f(f1(i)) 
mem_f(T;f1(i);fL)))
7. fL: T*
8.
t:T. mem_f(T;t;fL) 
f(t)
9.
i:
n. f(f1(i)) 
mem_f(T;f1(i);fL)
10. t: T
11. mem_f(T;t;fL)
f(t)
By: BackThru 8
Generated subgoals:None
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