| Ackermann’s Function | Index << >> |
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Lemma: If ⍺ ack ⍵ ←→ f⍢(3∘+) ⍵ , then (⍺+1)ack ⍵ ←→ f⍣(1+⍵)⍢(3∘+) 1 . ⍢ is the under or dual operator where (f⍢g) y ←→ g⍣¯1 f g y . ⍣ is the power operator where (f⍣n) ⍵ ←→ f … f ⍵ (n times). 3∘+ is + curried (Curry-ed?) with a left argument of 3. |