File size: 112 Bytes
197785f
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
new (A → D ∧ C) → (D ∧ B → (B ∧ A → B))
intro
intro
cases 1
intro
cases 4
cases 1
cases 4
exact 3