Let \(M\) be a matroid, let \(\ell:E(M)\to G\) be a labeling of its elements by an abelian group, and let \(F\subseteq G\) be finite. A base is \emph{\(F\)-avoiding} if the label sum of its elements is not in $F$. We prove that, for arbitrary costs, a min-cost \(F\)-avoiding base can be obtained from any min-cost … Read more
For a strongly convex unconstrained minimization problem, Newton’s method with a line search offers rapid convergence to a minimizer by incorporating second-order infor- mation. However, for a general unconstrained problem the Hessian need not be positive definite, which can lead to the inability to find a search direction or to search directions that fail to … Read more
This article introduces the Electric Vehicle Itinerary Planning with Activities (EV-IPA) problem, which jointly optimizes vehicle routing, parallel activity scheduling, non-linear charging decisions, and time-window constraints. This tight coupling is increasingly relevant as conversational in-car assistants let drivers negotiate itineraries in natural language. However, directly embedding continuous, non-linear state-of-charge dynamics into a discrete decision space … Read more
We consider a network of finitely many agents aiming to cooperatively solve a convex-concave min-max problem combining nonsmooth terms with a smooth saddle function whose partial gradients are only locally Lipschitz continuous. Without requiring prior knowledge of the local Lipschitz moduli of the partial gradients, we propose a distributed proximal-reflected-gradient algorithm which incorporates a distributed … Read more
We propose GenericILS, a general-purpose heuristic framework for generating high-quality upper bounds for Vehicle Routing Problems whose pricing subproblems are modeled, in column-generation-based exact algorithms, as resource-constrained shortest path problems described through Resource Extension Functions (REFs), the standard device for encoding constraints in branch-and-price algorithms. GenericILS reuses REFs implemented for the exact method, without a … Read more
Contact-rich robotic insertion is challenging because uncertainty in alignment, friction, and contact conditions can lead to unsuccessful assembly, excessive contact forces, and jamming. Designing a reliable controller therefore requires balancing insertion performance, robustness, and recovery from unexpected contact. In this paper, we propose PSO+TR, a derivative-free optimization (DFO) method that combines the exploratory search of … Read more
The branch-and-cut paradigm has led to effective solvers for a wide range of mathematical optimization problems. Despite significant theoretical work on pure branching and pure cutting, less is known about their interaction. We study an extended abstract branch-and-cut model to investigate tradeoffs between branching and cutting, including the time to generate cuts. We prove that, … Read more
The unpublished 1990 technical report reproduced here introduced the $t$-reinforced $k$-fence inequalities, the first facets of the acyclic subgraph polytope that are not rank inequalities: each simple $k$-fence induces $k-2$ of them, one for each $1\le t\le k-2$. The report proved this with the spectral method, using a coherent configuration and computer algebra. It went … Read more
Matrix assembly layouts provide manufacturing flexibility under product variety and demand volatility through locally reconfigurable production stations. Periodic redesign exploits this flexibility, yet existing models allow only annual revisions. Finer calendars expose a flexibility-commitment trade-off: advance layout commitments support coordination, supplier agreements, and discounts. We introduce the layout revision timing problem, jointly choosing revision points … Read more
We study decentralized minimization of sums of smooth strongly convex functions, one per agent, with communication restricted to neighbors in a graph. Existing decentralized algorithms typically emulate a {\it centralized} method; {\it the network serves only to exchange information}, from which agents approximate the global quantities that the method needs. This paper breaks with this … Read more