About the Structure of the Integer Cone and Its Application to Bin Packing

We consider the bin packing problem with d different item sizes and revisit the structure theorem given by Goemans and Rothvoß about solutions of the integer cone. We present new techniques on how solutions can be modified and give a new structure theorem that relies on the set of vertices of the underlying integer polytope. As a result of our new structure theorem, we obtain an algorithm for the bin packing problem with running time [Formula: see text], where V is the set of vertices of the integer knapsack polytope, and [Formula: see text] is the encoding length of the bin packing instance. The algorithm is fixed-parameter tractable, parameterized by the number of vertices of the integer knapsack polytope [Formula: see text]. This shows that the bin packing problem can be solved efficiently when the underlying integer knapsack polytope has an easy structure (i.e., has a small number of vertices). Furthermore, we show that the presented bounds of the structure theorem are asymptotically tight. We give a construction of bin packing instances using new structural insights and classical number theoretical theorems which yield the desired lower bound.

Integer Points in Knapsack Polytopes and $s$-Covering Radius

Given a matrix $A\in \mathbb{Z}^{m\times n}$ satisfying certain regularity assumptions, we consider for a positive integer $s$ the set ${\mathcal F}_s(A)\subset \mathbb{Z}^m$ of all vectors $b\in \mathbb{Z}^m$ such that the associated knapsack polytope\begin{equation*}P(A, b)=\{ x \in \mathbb{R}^n_{\ge 0}: A x= b\}\end{equation*}contains at least $s$ integer points. We present lower and upper bounds on the so called diagonal $s$-Frobenius number associated to the set ${\mathcal F}_s(A)$. In the case $m=1$ we prove an optimal lower bound for the $s$-Frobenius number, which is the largest integer $b$ such that $P(A,b)$ contains less than $s$ integer points.