How could I derive the following proposition:
$$ ((A \rightarrow B) \rightarrow A) \rightarrow A ) $$
using any of the following axioms:
1) $A→(B→A)$
2) $(A→(B→C))→((A→B)→(A→C))$
3) $((¬B)→(¬A))→(A→B)$
How could I derive the following proposition:
$$ ((A \rightarrow B) \rightarrow A) \rightarrow A ) $$
using any of the following axioms:
1) $A→(B→A)$
2) $(A→(B→C))→((A→B)→(A→C))$
3) $((¬B)→(¬A))→(A→B)$