Classification of maximizers of the embedding-time functional

Classify, for all sufficiently large finite \(k\), the permutations maximizing \(\beta(\pi)\) over \(\Pi_k\), and determine whether these extremizers admit a simple description, possibly through their associated tree representations.

Background

The maximum βk+=maxπΠkβ(π)\beta_k^+=\max_{\pi\in\Pi_k}\beta(\pi) has an effective dynamic program, so maximizers can be constructed for each fixed kk. However, the authors do not know whether the resulting permutations form a recognizable family. They note that the known constructions are neither close to monotone nor approximately uniformly random and may instead be characterized by recursive tree structure.

References

Although eq:beta+ readily yields a dynamic program for \beta_k+ that also gives constructions of maximizers for any fixed k, it is unclear whether the resulting examples belong to a simple family.

Online Permutation Embedding: Optimal Stopping and Scaling Laws  (2608.19050 - Altschuler et al., 19 Aug 2026) in Section 1, subsection "Open problems", Question following the discussion of maximizers

Determine g:=\limsup_{k \rightarrow \infty} \max_{\pi \in \Pi_k} \frac{\beta(\pi)}{n_c(\pi)}.

Online Permutation Embedding: Optimal Stopping and Scaling Laws  (2608.19050 - Altschuler et al., 19 Aug 2026) in Section 1, subsection "Open problems", Problem [Extremal online/offline gap]