A coefficient related to splay-to-root traversal, correct to thousands of decimal places

TL;DR

This paper investigates the minimal coefficient for splay-to-root traversal cost in binary trees, defining a new coefficient α, computing its first 3009 digits, and proposing conjectures about its properties.

Contribution

It introduces a new coefficient α related to traversal costs, computes its precise value to thousands of decimal places, and explores its theoretical properties and conjectures.

Findings

Computed α to 3009 decimal places with confirmed accuracy.

Established the inequality β ≥ 2 + α.

Proposed conjectures that β = 2 + α and that α is irrational.

Abstract

This paper takes another look at the cost of traversing a binary tree using repeated splay-to-root. This was shown to cost $O(n)$ (in rotations) by Tarjan and later, in different ways, by Elmasry and others. It would be interesting to know the minimal possible coefficient implied by the $O(n)$ cost; call this coefficient $\beta$. In this paper we define a related coefficient $\alpha$ describing the cost of splay-to-root traversal on maximal (i.e., complete) binary trees, and show that $\beta \geq 2 + \alpha$. We give the first 3009 digits of $\alpha$, including the decimal point, and show that every digit is correct. We make two conjectures: first, that $\beta = 2 + \alpha$, and second, that $\alpha$ is irrational.