Projected proximal gradient trust-region algorithm for nonsmooth optimization
M. N. Dao, H. M. Phan, L. Roberts, arXiv preprint arXiv:2501.04889, 2025
Publications
You can also find my articles on my Google Scholar profile.
Preprints
Randomized Subspace Derivative-Free Optimization with Quadratic Models and Second-Order Convergence
C. Cartis, L. Roberts, arXiv preprint arXiv:2412.14431, 2024
Black-box Optimization Algorithms for Regularized Least-squares Problems
Y. Liu, K. H. Lam, L. Roberts, arXiv preprint arXiv:2407.14915, 2024
Journal Articles
An adaptively inexact first-order method for bilevel optimization with application to hyperparameter learning
M. S. Salehi, S. Mukherjee, L. Roberts, M. J. Ehrhardt, SIAM Journal on Mathematics of Data Science, 2025
Neutron beam shaping by ghost projection
A. M. Kingston, A. Aminzadeh, L. Roberts, J. M. C. Brown, F. Salvemini, J. J. Bevitt, U. Garbe, D. M. Paganin, Physical Review A, 2025
High-resolution X-ray scanning with a diffuse Huffman-patterned probe to reduce radiation damage
A. Aminzadeh, A. M. Kingston, L. Roberts, D. M. Paganin, T. C. Petersen, I. D. Svalbe, Journal of Synchrotron Radiation, 2025
Model Construction for Convex-Constrained Derivative-Free Optimization
L. Roberts, SIAM Journal on Optimization, 2025
Expected decrease for derivative-free algorithms using random subspaces
W. Hare, L. Roberts, C. W. Royer, Mathematics of Computation, 2024
Non-Uniform Smoothness for Gradient Descent
A. Berahas, L. Roberts, F. Roosta, Transactions on Machine Learning Research, 2024
Analyzing Inexact Hypergradients for Bilevel Learning
M. J. Ehrhardt, L. Roberts, IMA Journal of Applied Mathematics, 2023
Direct search based on probabilistic descent in reduced spaces
L. Roberts, C. W. Royer, SIAM Journal on Optimization, 2023
Mask design, fabrication, and experimental ghost imaging applications for patterned X-ray illumination
A. Aminzadeh, L. Roberts, B. Young, C. Chiang, I. D. Svalbe, D. M. Paganin, A. M. Kingston, Optics Express, 2023
Optimizing illumination patterns for classical ghost imaging
A. M. Kingston, A. Aminzadeh, L. Roberts, D. Pelliccia, I. D. Svalbe, D. M. Paganin, Physical Review A, 2023
Furnace Vestibule Heat Transport Models
M. J. McGuinness, B. J. Cox, B. Kalyanaraman, K. B. Kiradjiev, R. Gonzalez-Farina, C. Z. W. Hassell Sweatman, L. Roberts, D. I. Pontin, E. J. Bissaker, S. K. Irvine, D. R. Jenkins, I. J. Taggart, ANZIAM Journal, 2023
On the selection of the weighting parameter value in optimizing Eucalyptus globulus pulp yield models based on NIR spectra
Y. Zhen, T. X. Ho, L. Roberts, L. R. Schimleck, A. Sinha, Wood Science and Technology, 2022
PyCUTEst: an open source Python package of optimization test problems
J. Fowkes, L. Roberts, A. Bűrmen, Journal of Open Source Software, 2022
Model-Based Derivative-Free Methods for Convex-Constrained Optimization
M. Hough, L. Roberts, SIAM Journal on Optimization, 2022
A Simplified Convergence Theory for Byzantine Resilient Stochastic Gradient Descent
L. Roberts, E. Smyth, EURO Journal on Computational Optimization, 2022
Scalable Subspace Methods for Derivative-Free Nonlinear Least-Squares Optimization
C. Cartis, L. Roberts, Mathematical Programming, 2022
Does Model Calibration Reduce Uncertainty in Climate Projections?
S. F. B. Tett, J. M. Gregory, N. Freychet, C. Cartis, M. J. Mineter, L. Roberts, Journal of Climate, 2021
Escaping local minima with local derivative-free methods: a numerical investigation
C. Cartis, L. Roberts, O. Sheridan-Methven, Optimization, 2021
Inexact Derivative-Free Optimization for Bilevel Learning
M. J. Ehrhardt, L. Roberts, Journal of Mathematical Imaging and Vision, 2021
Improving the Flexibility and Robustness of Model-Based Derivative-Free Optimization Solvers
C. Cartis, J. Fiala, B. Marteau, L. Roberts, ACM Transactions on Mathematical Software, 2019
A Derivative-Free Gauss-Newton Method
C. Cartis, L. Roberts, Mathematical Programming Computation, 2019
A heat and mass transfer study of carbon paste baking
L. Roberts, E. Nordgård-Hansen, Ø. Mikkelsen, S. A. Halvorsen, R. A. Van Gorder, International Communications in Heat and Mass Transfer, 2017
Conference Papers
Bilevel Learning with Inexact Stochastic Gradients
M. S. Salehi, S. Mukherjee, L. Roberts, M. J. Ehrhardt, Scale Space and Variational Methods in Computer Vision (SSVM), 2025
Efficient Hyperparameter Tuning with Dynamic Accuracy Derivative-Free Optimization
M. J. Ehrhardt, L. Roberts, 12th OPT Workshop on Optimization for Machine Learning (NeurIPS 2020), 2020
Scalable Derivative-Free Optimization for Nonlinear Least-Squares Problems
C. Cartis, T. Ferguson, L. Roberts, Workshop on "Beyond first-order methods in ML systems", 37th International Conference on Machine Learning (ICML 2020), 2020
Technical Reports
Capturing the Purpose of Websites
M. Bazzi et al, Alan Turing Institute Data Study Group, 2018
Cable Routing on Ships
A. Avdzhieva et al, 136th European Study Group with Industry, 2018
Optimising the Design of Polythene Hydroponics Beds
A. Champneys et al, Agri-Food Study Group with Industry, 2017
Derivative-Free Optimisation for Data Fitting
L. Roberts, InFoMM CDT Report, 2016
Flow dynamics in complex buildings (airports and rail stations)
C. Sargent et al, 116th European Study Group with Industry, 2016
Thesis
Derivative-Free Algorithms for Nonlinear Optimisation Problems
L. Roberts, PhD Thesis, University of Oxford, 2019