State-of-the-art exact methods for the Maximum Cut problem are based on solving linear and semidefinite programming relaxations embedded into a branch-and-bound algorithm. For linear programming formulations, it was shown recently that it is thereby sufficient to enforce the integrality of the variables associated with the edges of a spanning tree. Our first contribution is to … Read more
We give an exact algorithm for minimizing an arbitrary rational quadratic polynomial xTQx+ cTx+ γ over the integer points of a bounded rational polyhedron Ax ≤b. For n variables and m inequalities, the running time is 2O(n log(n+1))(m+ 1)O(n)φ_{A,Q}^O(n)(1 + φ)O(1), where φ_{A,Q} is one plus the maximum binary encoding length of an entry of … Read more
This paper investigates the Flying Sidekick Traveling Salesman Problem (FSTSP), and proposes an efficient Adaptive Large Neighborhood Search (ALNS) algorithm. Our proposed framework operates directly on a complete solution representation, eliminating the reconstruction step required by indirect encodings and making temporal information immediately accessible during the search process. A stage-based mechanism is introduced to efficiently … Read more
We develop a few calculus rules to compute or lower bound the facial distance of a polytope. We illustrate our calculus rules on various popular polytopes. In particular, we provide a lower bound on the facial distance of the Birkhoff polytope. CitationWorking paper. Tepper School of Business. Carnegie Mellon UniversityArticleDownload View PDF
For integer activities, conditioning on the support makes a fixed-charge objective affine. If every support-conditioned cell is integral, an optimal solution is a vertex of its cell for arbitrary fixed charges and marginal rates. A totally unimodular constraint matrix with integral data guarantees this condition. This surviving property is weaker than the classical conclusions. A … Read more
The symmetry measure of a convex body \(S\subset\mathbb{R}^n\) is given by: \(\mathrm{sym}(S):=\max\{\alpha\ge0:\ \mathrm{there\ exists}\ x\in S\ \mathrm{such\ that}\ -\alpha(S-x)\subseteq S-x\}\), where such an \(x\) is called a Minkowski center. We prove that every convex body \(S\) admits a \(\sqrt{\frac{n}{\mathrm{sym}(S)}}\)-rounding of \(S\), namely, there exists an origin-centered ellipsoid \(E\) and a center \(c\) such that the … Read more
Feature-based newsvendor models use observable covariates to tailor inventory decisions, aiming to balance holding and shortage costs under demand uncertainty. However, high-dimensional feature sets often hinder interpretability and inflate data collection and implementation costs. This paper studies variable selection for the feature-based newsvendor problem under a hard cardinality constraint on the number of selected features. … Read more
We give a simple example that disproves the following 2015 conjecture of Lacoste-Julien and Jaggi concerning the pyramidal width (aka facial distance): The pyramidal width of a set of vertices is non-increasing when another vertex is added (assuming that all previous points remain vertices). In contrast to the recent example by Zhao (arXiv:2607.29555), our counterexample … Read more
We address the classical Dantzig – Fulkerson – Johnson formulation of the symmetric metric Traveling Salesman Problem and study the integrality gap of its linear relaxation, namely the Subtour Elimination Problem (SEP). This integrality gap is conjectured to be 4/3. We prove that, when solving a problem on n nodes, if the optimal SEP solution … Read more
The Ramsey number R(m,n) is the smallest order at which every red-blue edge coloring of a complete graph must contain a blue clique (a complete subgraph) of size m or a red clique of size n. Determining these numbers exactly is extremely hard, and even certifying a lower bound requires exhibiting an explicit coloring that … Read more