proximal gradient methods

Barzilai-Borwein-like rules in proximal gradient schemes for ℓ1−regularized problems

  • Serena Crisci
  • Simone Rebegoldi
  • Gerardo Toraldo
  • Marco Viola
    • Categories Convex and Nonsmooth Optimization, Nonlinear Optimization Tags , ,

    We propose a novel steplength selection rule in proximal gradient methods for minimizing the sum of a differentiable function plus an ℓ1-norm penalty term. The proposed rule modifies one of the classical Barzilai-Borwein steplength, extending analogous results obtained in the context of gradient projection methods for constrained optimization. We analyze the spectral properties of the … Read more

    ”Active-set complexity” of proximal gradient: How long does it take to find the sparsity pattern?

  • Warren Hare
  • Mark Schmidt
  • Julie Nutini
    • Categories Convex and Nonsmooth Optimization, Convex Optimization, Nonsmooth Optimization Tags , ,

    Proximal gradient methods have been found to be highly effective for solving minimization problems with non-negative constraints or L1-regularization. Under suitable nondegeneracy conditions, it is known that these algorithms identify the optimal sparsity pattern for these types of problems in a finite number of iterations. However, it is not known how many iterations this may … Read more