Constructing certain families of $\mathbf{3}$-polytopal graphs

TL;DR

This paper determines minimal vertex counts for certain 3-polytopal graphs with specified degree properties, and provides algorithms for constructing such graphs with asymptotically optimal size.

Contribution

It introduces algorithms to construct 3-polytopal graphs with prescribed degree distributions, achieving near-minimal vertex counts and generalizing to related polytope problems.

Findings

Minimal vertex count for given degree constraints identified

Algorithms for constructing 3-polytopal graphs with specified degrees developed

Constructed graphs are asymptotically optimal in size

Abstract

Let $n\geq 3$ and $r_n$ be a $3$-polytopal graph such that for every $3\leq i\leq n$, $r_n$ has at least one vertex of degree $i$. We find the minimal vertex count for $r_n$. We then describe an algorithm to construct the graphs $r_n$. A dual statement may be formulated for faces of $3$-polytopes. The ideas behind the algorithm generalise readily to solve related problems. Moreover, given a $3$-polytope $t_l$ comprising a vertex of degree $i$ for all $3\leq i\leq l$, $l$ fixed, we define an algorithm to output for $n>l$ a $3$-polytope $t_n$ comprising a vertex of degree $i$, for all $3\leq i\leq n$, and such that the initial $t_l$ is a subgraph of $t_n$. The vertex count of $t_n$ is asymptotically optimal, in the sense that it matches the aforementioned minimal vertex count up to order of magnitude, as $n$ gets large. In fact, we only lose a small quantity on the coefficient of the second highest term, and this quantity may be taken as small as we please, with the tradeoff of first constructing an accordingly large auxiliary graph.