Search Results for author: Ting Kei Pong

Found 12 papers, 1 papers with code

A Newton-CG based augmented Lagrangian method for finding a second-order stationary point of nonconvex equality constrained optimization with complexity guarantees

no code implementations9 Jan 2023 Chuan He, Zhaosong Lu, Ting Kei Pong

In particular, we first propose a new Newton-CG method for finding an approximate SOSP of unconstrained optimization and show that it enjoys a substantially better complexity than the Newton-CG method [56].

Kurdyka-Łojasiewicz exponent via inf-projection

no code implementations10 Feb 2019 Peiran Yu, Guoyin Li, Ting Kei Pong

In addition, for nonconvex models, we show that the KL exponent of many difference-of-convex functions can be derived from that of their natural majorant functions, and the KL exponent of the Bregman envelope of a function is the same as that of the function itself.

A refined convergence analysis of pDCA$_e$ with applications to simultaneous sparse recovery and outlier detection

no code implementations19 Apr 2018 Tianxiang Liu, Ting Kei Pong, Akiko Takeda

Moreover, for a large class of loss functions and regularizers, the KL exponent of the corresponding potential function are shown to be 1/2, which implies that the pDCA$_e$ is locally linearly convergent when applied to these problems.

Outlier Detection

Iteratively reweighted $\ell_1$ algorithms with extrapolation

no code implementations22 Oct 2017 Peiran Yu, Ting Kei Pong

Iteratively reweighted $\ell_1$ algorithm is a popular algorithm for solving a large class of optimization problems whose objective is the sum of a Lipschitz differentiable loss function and a possibly nonconvex sparsity inducing regularizer.

A successive difference-of-convex approximation method for a class of nonconvex nonsmooth optimization problems

no code implementations16 Oct 2017 Tianxiang Liu, Ting Kei Pong, Akiko Takeda

We consider a class of nonconvex nonsmooth optimization problems whose objective is the sum of a smooth function and a finite number of nonnegative proper closed possibly nonsmooth functions (whose proximal mappings are easy to compute), some of which are further composed with linear maps.

A Non-monotone Alternating Updating Method for A Class of Matrix Factorization Problems

no code implementations18 May 2017 Lei Yang, Ting Kei Pong, Xiaojun Chen

Finally, we conduct some numerical experiments using real datasets to compare our method with some existing efficient methods for non-negative matrix factorization and matrix completion.

Matrix Completion

Further properties of the forward-backward envelope with applications to difference-of-convex programming

no code implementations1 May 2016 Tianxiang Liu, Ting Kei Pong

In this paper, we further study the forward-backward envelope first introduced in [28] and [30] for problems whose objective is the sum of a proper closed convex function and a twice continuously differentiable possibly nonconvex function with Lipschitz continuous gradient.

Calculus of the exponent of Kurdyka-Łojasiewicz inequality and its applications to linear convergence of first-order methods

no code implementations9 Feb 2016 Guoyin Li, Ting Kei Pong

Since many existing local convergence rate analysis for first-order methods in the nonconvex scenario relies on the KL exponent, our results enable us to obtain explicit convergence rate for various first-order methods when they are applied to a large variety of practical optimization models.

Linear Convergence of Proximal Gradient Algorithm with Extrapolation for a Class of Nonconvex Nonsmooth Minimization Problems

1 code implementation31 Dec 2015 Bo Wen, Xiaojun Chen, Ting Kei Pong

In this paper, we study the proximal gradient algorithm with extrapolation for minimizing the sum of a Lipschitz differentiable function and a proper closed convex function.

Douglas-Rachford splitting for nonconvex optimization with application to nonconvex feasibility problems

no code implementations30 Sep 2014 Guoyin Li, Ting Kei Pong

We then apply our nonconvex DR splitting method to finding a point in the intersection of a closed convex set $C$ and a general closed set $D$ by minimizing the squared distance to $C$ subject to $D$.

Penalty methods for a class of non-Lipschitz optimization problems

no code implementations9 Sep 2014 Xiaojun Chen, Zhaosong Lu, Ting Kei Pong

We consider a class of constrained optimization problems with a possibly nonconvex non-Lipschitz objective and a convex feasible set being the intersection of a polyhedron and a possibly degenerate ellipsoid.

Global convergence of splitting methods for nonconvex composite optimization

no code implementations3 Jul 2014 Guoyin Li, Ting Kei Pong

In this paper, we examined two types of splitting methods for solving this nonconvex optimization problem: alternating direction method of multipliers and proximal gradient algorithm.

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