= Inverse Ackermann function
{title2=$\alpha(n)$}
For the displayed <Ackermann function> convention, one possible inverse-growth scale is $\alpha(n)=\min\{m\geq1:A(m,m)\geq n\}$ for positive <integers> $n$. It gives $\alpha(n)=1$ through $3$, $2$ from $4$ through $7$, and $3$ from $8$ through $61$. Several <inverse Ackermann function> conventions occur in <algorithm> analysis; changing convention can shift these small values without changing the very slow growth relevant to the <disjoint-set data structure>. This inverse-growth definition does not invert a two-variable <function> as an ordinary one-variable <inverse function>.
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