Riemannian optimization with finite-difference gradient approximations

Derivative-free Riemannian optimization (DFRO) aims to minimize an objective function using only function evaluations, under the constraint that the decision variables lie on a Riemannian manifold. The rapid increase in problem dimensions over the years calls for computationally cheap DFRO algorithms, that is, algorithms requiring as few function evaluations and retractions as possible. We propose … Read more

A Marginal Reliability Impact Based Accreditation Framework for Capacity Markets

This paper presents a Marginal Reliability Impact (MRI) based resource accreditation framework for capacity market design. Under this framework, a resource is accredited based on its marginal impact on system reliability, thus aligning the resource’s accreditation value with its reliability contribution. A key feature of the MRI-based accreditation is that the accredited capacities supplied by … Read more

Non-Convex Self-Concordant Functions: Practical Algorithms and Complexity Analysis

We extend the standard notion of self-concordance to non-convex optimization and develop a family of second-order algorithms with global convergence guarantees. In particular, two function classes – weakly self-concordant functions and F-based self-concordant functions – generalize the self-concordant framework beyond convexity, without assuming the Lipschitz continuity of the gradient or Hessian. For these function classes, … Read more

Infeasibility Certificates from Superadditive Functions for Mixed-Integer Programs

We present a constructive procedure for certifying the infeasibility of a mixed-integer program (MIP) using recursion on a sequence of sets that describe the sets of barely feasible right-hand sides. Each of these sets corresponds to a monotonic superadditive function, and the pointwise limit of this sequence is a functional certificate for MIP infeasibility. Our … Read more

A first approximation algorithm for the Bin Packing Problem with Setups

We study constant-factor approximation algorithms for the Bin Packing Problem with Setups (BPPS). First, we show that adaptations of classical BPP heuristics can have arbitrarily poor worst-case performance on BPPS instances. Then, we propose a two-phase heuristic for the BPPS that applies an α-approximation algorithm for the BPP to the items of each class and … Read more

Iteration complexity of the Difference-of-Convex Algorithm for unconstrained optimization: a simple proof

We propose a simple proof of the worst-case iteration complexity for the Difference of Convex functions Algorithm (DCA) for unconstrained minimization, showing that the global rate of convergence of the norm of the objective function’s gradients at the iterates converge to zero like $o(1/k)$. A small example is also provided indicating that the rate cannot … Read more

Non-convex stochastic compositional optimization under heavy-tailed noise

This paper investigates non-convex stochastic compositional optimization under heavy-tailed noise, where the stochastic noise exhibits bounded $p$th moment with $p\in(1,2]$. The main challenges arise from biased gradient estimates of the objective and the violation of the standard bounded-variance assumption. To address these issues, we propose a generic algorithm framework of Normalized Stochastic Compositional Gradient methods … Read more

Tilt Stability on Riemannian Manifolds with Application to Convergence Analysis of Generalized Riemannian Newton Method

We generalize tilt stability, a fundamental concept in perturbation analysis of optimization problems in Euclidean spaces, to the setting of Riemannian manifolds. We prove the equivalence of the following conditions: Riemannian tilt stability, Riemannian variational strong convexity, Riemannian uniform quadratic growth, local strong monotonicity of Riemannian subdifferential, strong metric regularity of Riemannian subdifferential, and positive … Read more

An efficient penalty decomposition algorithm for minimization over sparse symmetric sets

This paper proposes an improved quasi-Newton penalty decomposition algorithm for the minimization of continuously differentiable functions, possibly nonconvex, over sparse symmetric sets. The method solves a sequence of penalty subproblems approximately via a two-block decomposition scheme: the first subproblem admits a closed-form solution without sparsity constraints, while the second subproblem is handled through an efficient … Read more