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This paper focuses on a class of zero-norm composite optimization problems. For this class of nonconvex nonsmooth problems, we establish the Kurdyka–Łojasiewicz property of exponent being a half for its objective function under a suitable assumption and provide some examples to illustrate that such an assumption is not very restricted which, in particular, involve the zero-norm regularized or constrained piecewise linear–quadratic function, the zero-norm regularized or constrained logistic regression function, the zero-norm regularized or constrained quadratic function over a sphere.

This article addresses the role of social innovation in ageing communities. Two cases are considered, namely the Life 2.0 project that focuses on generating information and communication technology services for ageing individuals and groups across Europe, while the second case is a project that was conducted with the BoAi aged care facility in China in which food services were (re)designed through insights stemming from the community. A comparative analysis will investigate how ageing communities collaboratively work with stakeholders, including designers and other professionals, to develop new services with the elderly. The comparative analysis presents insights into the role of ageing communities in service design processes and their roles as co-creators in new futures.

We derive some conditions for a feasible point to be the isolated optimal solution for three classes of nuclear norm optimization problems by using the isolated calmness of two set-valued mappings:...

This paper is concerned with a class of optimization problems with the nonnegative orthogonal constraint, in which the objective function is $L$-smooth on an open set containing the Stiefel manifold ${\rm St}(n,r)$. We derive a locally Lipschitzian error bound for the feasible points without zero rows when $n>r>1$, and when $n>r=1$ or $n=r$ achieve a global Lipschitzian error bound. Then, we show that the penalty problem induced by the elementwise $\ell_1$-norm distance to the nonnegative cone is a global exact penalty, and so is the one induced by its Moreau envelope under a lower second-order calmness of the objective function. A practical penalty algorithm is developed by solving approximately a series of smooth penalty problems with a retraction-based nonmonotone line-search proximal gradient method, and any cluster point of the generated sequence is shown to be a stationary point of the original problem. Numerical comparisons with the ALM \citep{Wen13} and the exact penalty method \citep{JiangM22} indicate that our penalty method has an advantage in terms of the quality of solutions despite taking a little more time., 34 pages, and 6 figures

This paper addresses the social phenomenon of ageing and emphasizes the importance of past experiences of ageing individuals when creating new solutions to deal with the issue of elderly ca...

This paper is concerned with the strong calmness of the KKT solution mapping for a class of canonically perturbed conic programming, which plays a central role in achieving fast convergence under situations when the Lagrange multiplier associated to a solution of these conic optimization problems is not unique. We show that the strong calmness of the KKT solution mapping is equivalent to a local error bound for solutions of perturbed KKT system, and is also equivalent to the pseudo-isolated calmness of the stationary point mapping along with the calmness of the multiplier set map at the corresponding reference point. Sufficient conditions are also provided for the strong calmness by establishing the pseudo-isolated calmness of the stationary point mapping in terms of the noncriticality of the associated multiplier, and the calmness of the multiplier set mapping in terms of a relative interior condition for the multiplier set. These results cover and extend the existing ones in \cite{Hager99,Izmailov12} for nonlinear programming and in \cite{Cui16,Zhang17} for semidefinite programming., 21 pages

For a finite convex function, we show that its subdifferential mapping is metrically subregular if and only if the normal cone mapping to its epigraph is metrically subregular. Then, for the nonconvex composition $$\psi =\theta \circ G$$ where G is a continuously differentiable mapping and $$\theta $$ is an extended real-valued function, we develop a criterion to identify the metric subregularity and calmness of the subdifferential mapping of $$\psi $$ in terms of that of the subdifferential mapping of $$\theta $$ . Together with the existing results, we obtain the metric subregularity of the normal cone mapping to the vector and matrix p-order cone $$K_p$$ and the conic constraint system $$g^{-1}(K_p)$$ with $$p\in [1,2]\cup \{+\infty \}$$ , where g is a continuously differentiable mapping. We also establish the calmness of the normal cone mapping to $$K_p$$ and $$g^{-1}(K_p)$$ with $$p\in [2,+\infty ]\cup \{1\}$$ .

This paper focuses on the characterization for the regular and limiting normal cones to the graph of the subdifferential mapping of the nuclear norm, which is essential to derive optimality conditions for the equivalent MPEC (mathematical program with equilibrium constraints) reformulation of rank minimization problems.

Wasserstein barycenter is the centroid of a collection of discrete probability distributions which minimizes the average of the $$\ell _2$$ -Wasserstein distance. This paper focuses on the computation of Wasserstein barycenters under the case where the support points are free, which is known to be a severe bottleneck in the D2-clustering due to the large scale and nonconvexity. We develop an inexact proximal alternating minimization (iPAM) method for computing an approximate Wasserstein barycenter, and provide its global convergence analysis. This method can achieve a good accuracy with a reduced computational cost when the unknown support points of the barycenter have low cardinality. Numerical comparisons with the 3-block B-ADMM in Ye et al. (IEEE Trans Signal Process 65:2317–2332, 2017) and an alternating minimization method involving the LP subproblems on synthetic and real data show that the proposed iPAM can yield comparable even a little better objective values in less CPU time, and hence, the computed barycenter will render a better role in the D2-clustering.

This paper is concerned with high-dimensional error-in-variables regression that aims at identifying a small number of important interpretable factors for corrupted data from many applications where measurement errors or missing data can not be ignored. Motivated by CoCoLasso due to Datta and Zou \cite{Datta16} and the advantage of the zero-norm regularized LS estimator over Lasso for clean data, we propose a calibrated zero-norm regularized LS (CaZnRLS) estimator by constructing a calibrated least squares loss with a positive definite projection of an unbiased surrogate for the covariance matrix of covariates, and use the multi-stage convex relaxation approach to compute the CaZnRLS estimator. Under a restricted eigenvalue condition on the true matrix of covariates, we derive the $\ell_2$-error bound of every iterate and establish the decreasing of the error bound sequence, and the sign consistency of the iterates after finite steps. The statistical guarantees are also provided for the CaZnRLS estimator under two types of measurement errors. Numerical comparisons with CoCoLasso and NCL (the nonconvex Lasso proposed by Poh and Wainwright \cite{Loh11}) demonstrate that CaZnRLS not only has the comparable or even better relative RSME but also has the least number of incorrect predictors identified.

This paper proposes a mechanism to produce equivalent Lipschitz surrogates for zero-norm and rank optimization problems by means of the global exact penalty for their equivalent mathematical programs with an equilibrium constraint (MPECs). Specifically, we reformulate these combinatorial problems as equivalent MPECs by the variational characterization of the zero-norm and rank function, show that their penalized problems, yielded by moving the equilibrium constraint into the objective, are the global exact penalization, and obtain the equivalent Lipschitz surrogates by eliminating the dual variable in the global exact penalty. These surrogates, including the popular SCAD function in statistics, are also difference of two convex functions (D.C.) if the function and constraint set involved in zero-norm and rank optimization problems are convex. We illustrate an application by designing a multi-stage convex relaxation approach to the rank plus zero-norm regularized minimization problem.

This paper is concerned with the least squares loss constrained low-rank plus sparsity optimization problems that seek a low-rank matrix and a sparse matrix by minimizing a positive combination of the rank function and the zero norm over a least squares constraint set describing the observation or prior information on the target matrix pair. For this class of NP-hard optimization problems, we propose a two-stage convex relaxation approach by the majorization for suitable locally Lipschitz continuous surrogates, which have a remarkable advantage in reducing the error yielded by the popular nuclear norm plus $$\ell _1$$l1-norm convex relaxation method. Also, under a suitable restricted eigenvalue condition, we establish a Frobenius norm error bound for the optimal solution of each stage and show that the error bound of the first stage convex relaxation (i.e. the nuclear norm plus $$\ell _1$$l1-norm convex relaxation), can be reduced much by the second stage convex relaxation, thereby providing the theoretical guarantee for the two-stage convex relaxation approach. We also verify the efficiency of the proposed approach by applying it to some random test problems and some problems with real data arising from specularity removal from face images, and foreground/background separation from surveillance videos.

We present a real-time complex amplitude reconstruction method for determining the beam propagation ratio M

This paper concerns with the graphical derivative of the normals to the conic constraint $g(x)\in\!K$, where $g\!:\mathbb{X}\to\mathbb{Y}$ is a twice continuously differentiable mapping and $K\subseteq\mathbb{Y}$ is a nonempty closed convex set assumed to be $C^2$-cone reducible. Such a generalized derivative plays a crucial role in characterizing isolated calmness of the solution maps to generalized equations whose multivalued parts are modeled via the normals to the nonconvex set $\Gamma=g^{-1}(K)$. The main contribution of this paper is to provide an exact characterization for the graphical derivative of the normals to this class of nonconvex conic constraints under an assumption without requiring the nondegeneracy of the reference point as the papers \cite{Gfrerer17,Mordu15,Mordu151} do., Comment: 28pages

We utilize the spectral broadening of Yb-doped fiber lasers in the spectral beam combining scheme to develop an analytical model of the coupling efficiency, which forms a critical factor in evaluating the practicality of the beam combination system. The simulation results predict a trend similar to the measured ones. Via increasing the number of simulating lasers, the model can be extended to calculate the combining efficiency of the resulting multiple-beam-combination system and estimate the optimal output power and combining efficiency. Moreover, the analytical model is suitable to investigate key parameters of Yb-doped lasers and filters, which is beneficial in enhancing the combining efficiency.

This paper concerns with a noisy structured low-rank matrix recovery problem which can be modeled as a structured rank minimization problem. We reformulate this problem as a mathematical program with a generalized complementarity constraint (MPGCC), and show that its penalty version, yielded by moving the generalized complementarity constraint to the objective, has the same global optimal solution set as the MPGCC does whenever the penalty parameter is over a threshold. Then, by solving the exact penalty problem in an alternating way, we obtain a multi-stage convex relaxation approach. We provide theoretical guarantees for our approach under a mild restricted eigenvalue condition, by quantifying the reduction of the error and approximate rank bounds of the first stage convex relaxation (which is exactly the nuclear norm relaxation) in the subsequent stages and establishing the geometric convergence of the error sequence in a statistical sense. Numerical experiments are conducted for some structured low-rank matrix recovery examples to confirm our theoretical findings., Comment: 29 pages, 2 figures

It has been an open question whether the family of merit functions ψ p ( p > 1 ) \psi _p\ (p>1) , the generalized Fischer-Burmeister (FB) merit function, associated to the second-order cone is smooth or not. In this paper we answer it partly, and show that ψ p \psi _p is smooth for p ∈ ( 1 , 4 ) p\in (1,4) , and we provide the condition for its coerciveness. Numerical results are reported to illustrate the influence of p p on the performance of the merit function method based on ψ p \psi _p .

We present a fast , easy and real-time method for measuring the laser beam quality factor, M2 , using a spatial light modulator(SLM). We import computer-generated holograms into the spatial light modulator. Then the laser beams are reflected by the SLM and transfer through a fourier transform lens, composed into different kinds of modes which are received by a CCD. The M2 value can be obtained by analyzing and calculating the modal weighting coefficients of different modes. In this paper, two different kinds of softwares , Matlab and VirtualLab, are used to implement the numerical simulations of the experiment process, so that the feasibility of the algorithm can be proved. In the end, we set up the experimental platform and implement the experiments with measuring laser beam quality factor, M2 , using a he-ne laser as the light source. The comparison with the theoretical value and the simulative value proves the reliability of the experiments.

The rank function rank(.) is neither continuous nor convex which brings much difficulty to the solution of rank minimization problems. In this paper, we provide a unified framework to construct the approximation functions of rank(.), and study their favorable properties. Particularly, with two families of approximation functions, we propose a convex relaxation method for the rank minimization problems with positive semidefinite cone constraints, and illustrate its application by computing the nearest low-rank correlation matrix. Numerical results indicate that this convex relaxation method is comparable with the sequential semismooth Newton method (Li and Qi in SIAM J Optim 21:1641---1666, 2011) and the majorized penalty approach (Gao and Sun, 2010) in terms of the quality of solutions.

For a locally optimal solution to the nonlinear semidefinite programming problem, under Robinson's constraint qualification, we show that the nonsingularity of Clarke's Jacobian of the Fischer-Burmeister (FB) nonsmooth system is equivalent to the strong regularity of the Karush-Kuhn-Tucker point. Consequently, from Sun's paper [Math. Oper. Res., 31 (2006), pp. 761-776] the semismooth Newton method applied to the FB system may attain the locally quadratic convergence under the strong second order sufficient condition and constraint nondegeneracy.

We establish that the Fischer-Burmeister (FB) complementarity function andthenaturalresidual(NR)complementarityfunctionassociatedwiththesymmetric cone have the same growth, in terms of the classification of Euclidean Jordan alge- bras.This,ontheonehand,providesanaffirmativeanswertothesecondopenquestion proposed by Tseng (J Optim Theory Appl 89:17-37, 1996) for the matrix-valued FB and NR complementarity functions, and on the other hand, extends the third impor- tant inequality of Lemma 3.1 in the aforementioned paper to the setting of Euclidean Jordan algebras. It is worthwhile to point out that the proof is surprisingly simple.

We consider a class of derivative-free descent methods for solving the second-order cone complementarity problem (SOCCP). The algorithm is based on the Fischer–Burmeister (FB) unconstrained minimization reformulation of the SOCCP, and utilizes a convex combination of the negative partial gradients of the FB merit function ψFB as the search direction. We establish the global convergence results of the algorithm under monotonicity and the uniform Jordan P-property, and show that under strong monotonicity the merit function value sequence generated converges at a linear rate to zero. Particularly, the rate of convergence is dependent on the structure of second-order cones. Numerical comparisons are also made with the limited BFGS method used by Chen and Tseng (An unconstrained smooth minimization reformulation of the second-order cone complementarity problem, Math. Program. 104(2005), pp. 293–327), which confirm the theoretical results and the effectiveness of the algorithm.

We make a unified analysis of interior proximal methods of solving convex second-order cone programming problems. These methods use a proximal distance with respect to second-order cones which can be produced with an appropriate closed proper univariate function in three ways. Under some mild conditions, the sequence generated is bounded with each limit point being a solution, and global rates of convergence estimates are obtained in terms of objective values. A class of regularized proximal distances is also constructed which can guarantee the global convergence of the sequence to an optimal solution. These results are illustrated with some examples. In addition, we also study the central paths associated with these distance-like functions, and for the linear SOCP we discuss their relations with the sequence generated by the interior proximal methods. From this, we obtain improved convergence results for the sequence for the interior proximal methods using a proximal distance continuous at the boundary of second-order cones.

For the symmetric cone complementarity problem, we show that each stationary point of the unconstrained minimization reformulation based on the Fischer-Burmeister merit function is a solution to the problem, provided that the gradient operators of the mappings involved in the problem satisfy column monotonicity or have the Cartesian P"0-property. These results answer the open question proposed in the article that appeared in Journal of Mathematical Analysis and Applications 355 (2009) 195-215.

In this article, we show that a one-parametric class of SOC merit functions has a Lipschitz continuous gradient; and moreover, the Lipschitz constant is related to the parameter in this class of SOC merit functions. This fact will lay a building block when the merit function approach as well as the Newton-type method are employed for solving the second-order cone complementarity problem with this class of merit functions.

We consider an extended second-order cone linear complementarity problem (SOCLCP), including the generalized SOCLCP, the horizontal SOCLCP, the vertical SOCLCP, and the mixed SOCLCP as special cases. In this paper, we present some simple second-order cone constrained and unconstrained reformulation problems, and under mild conditions prove the equivalence between the stationary points of these optimization problems and the solutions of the extended SOCLCP. Particularly, we develop a proximal gradient descent method for solving the second-order cone constrained problems. This method is very simple and at each iteration makes only one Euclidean projection onto second-order cones. We establish global convergence and, under a local Lipschitzian error bound assumption, linear rate of convergence. Numerical comparisons are made with the limited-memory BFGS method for the unconstrained reformulations, which verify the effectiveness of the proposed method.

We present a smooth approximation for the generalized Fischer–Burmeister function where the 2-norm in the FB function is relaxed to a general p -norm ( p > 1 ), and establish some favorable properties for it — for example, the Jacobian consistency. With the smoothing function, we transform the mixed complementarity problem (MCP) into solving a sequence of smooth system of equations, and then trace a smooth path generated by the smoothing algorithm proposed by Chen (2000) [28] to the solution set. In particular, we investigate the influence of p on the numerical performance of the algorithm by solving all MCPLIP test problems, and conclude that the smoothing algorithm with p ∈ ( 1 , 2 ] has better numerical performance than the one with p > 2 .

In this paper, we consider a neural network model for solving the nonlinear complementarity problem (NCP). The neural network is derived from an equivalent unconstrained minimization reformulation of the NCP, which is based on the generalized Fischer-Burmeister function @f"p(a,b)[email protected]?(a,b)@?"p-(a+b). We establish the existence and the convergence of the trajectory of the neural network, and study its Lyapunov stability, asymptotic stability as well as exponential stability. It was found that a larger p leads to a better convergence rate of the trajectory. Numerical simulations verify the obtained theoretical results.

In this paper, we consider the problem of minimizing a sum of Tchebycheff norms @F(x)=@?"i"="1^m@?b"i-A"i^Tx@?"~, where A"i@?R^n^x^d and b"i@?R^d. We derive a smooth approximation of @F(x) by the entropy regularization technique, and convert the problem into a parametric family of strictly convex minimization. It turns out that the minimizers of these problems generate a trajectory that will go to the primal-dual solution set of the original problem as the parameter tends to zero. By this, we propose a smoothing algorithm to compute an @e-optimal primal-dual solution pair. The algorithm is globally convergent and has a quadratic rate of convergence. Numerical results are reported for a path-following version of the algorithm and made comparisons with those yielded by the primal-dual path-following interior point algorithm, which indicate that the proposed algorithm can yield the solutions with favorable accuracy and is comparable with the interior point method in terms of CPU time for those problems with m@?max{n,d}.

In this paper, we study the properties of the penalized Fischer-Burmeister (FB) second-order cone (SOC) complementarity function. We show that the function possesses similar desirable properties of the FB SOC complementarity function for local convergence; for example, with the function the second-order cone complementarity problem (SOCCP) can be reformulated as a (strongly) semismooth system of equations, and the corresponding nonsmooth Newton method has local quadratic convergence without strict complementarity of solutions. In addition, the penalized FB merit function has bounded level sets under a rather weak condition which can be satisfied by strictly feasible monotone SOCCPs or SOCCPs with the Cartesian R 01-property, although it is not continuously differentiable. Numerical results are included to illustrate the theoretical considerations.

In the paper [J.-S. Chen, S. Pan, A family of NCP-functions and a descent method for the nonlinear complementarity problem, Computational Optimization and Applications, 40 (2008) 389-404], the authors proposed a derivative-free descent algorithm for nonlinear complementarity problems (NCPs) by the generalized Fischer-Burmeister merit function: @j"p(a,b)=12[@?(a,b)@?"p-(a+b)]^2, and observed that the choice of the parameter p has a great influence on the numerical performance of the algorithm. In this paper, we analyze the phenomenon theoretically for a derivative-free descent algorithm which is based on a penalized form of @j"p and uses a different direction from that of Chen and Pan. More specifically, we show that the algorithm proposed is globally convergent and has a locally R-linear convergence rate, and furthermore, its convergence rate will become worse when the parameter p decreases. Numerical results are also reported for the test problems from MCPLIB, which further verify the theoretical results obtained.

In this paper, we extend the one-parametric class of merit functions proposed by Kanzow and Kleinmichel [C. Kanzow, H. Kleinmichel, A new class of semismooth Newton-type methods for nonlinear complementarity problems, Comput. Optim. Appl. 11 (1998) 227–251] for the nonnegative orthant complementarity problem to the general symmetric cone complementarity problem (SCCP). We show that the class of merit functions is continuously differentiable everywhere and has a globally Lipschitz continuous gradient mapping. From this, we particularly obtain the smoothness of the Fischer–Burmeister merit function associated with symmetric cones and the Lipschitz continuity of its gradient. In addition, we also consider a regularized formulation for the class of merit functions which is actually an extension of one of the NCP function classes studied by [C. Kanzow, Y. Yamashita, M. Fukushima, New NCP functions and their properties, J. Optim. Theory Appl. 97 (1997) 115–135] to the SCCP. By exploiting the Cartesian P-properties for a nonlinear transformation, we show that the class of regularized merit functions provides a global error bound for the solution of the SCCP, and moreover, has bounded level sets under a rather weak condition which can be satisfied by the monotone SCCP with a strictly feasible point or the SCCP with the joint Cartesian R 02 -property. All of these results generalize some recent important works in [J.-S. Chen, P. Tseng, An unconstrained smooth minimization reformulation of the second-order cone complementarity problem, Math. Program. 104 (2005) 293–327; C.-K. Sim, J. Sun, D. Ralph, A note on the Lipschitz continuity of the gradient of the squared norm of the matrix-valued Fischer–Burmeister function, Math. Program. 107 (2006) 547–553; P. Tseng, Merit function for semidefinite complementarity problems, Math. Program. 83 (1998) 159–185] under a unified framework.

We consider the Tikhonov regularization method for the second-order cone complementarity problem (SOCCP) with the Cartesian P 0 -property. We show that many results of the regularization method for the P 0 -nonlinear complementarity problem still hold for this important class of nonmonotone SOCCP. For example, under the more general setting, every regularized problem has the unique solution, and the solution trajectory generated is bounded if the original SOCCP has a nonempty and bounded solution set. We also propose an inexact regularization algorithm by solving the sequence of regularized problems approximately with the merit function approach based on Fischer–Burmeister merit function, and establish the convergence result of the algorithm. Preliminary numerical results are also reported, which verify the favorable theoretical properties of the proposed method.