in this paper, at rst for a given set of real or complex numbers  with nonnegative summation, we introduce some special conditions that with them there is no nonnegative tridiagonal matrix in which  is its spectrum. in continue we present some conditions for existence such nonnegative tridiagonal matrices.

In this paper we propose a simple model for the coupling behavior of the human spine that is capable of exhibiting anatomically correct motions of the vertebrae in virtual mannequins. Such a model transparently integrates in our inverse kinematics framework as it couples standard swing and revolute joint models. The adjustment of the joints due to the coupling is made with several simple (in)eq...

Consider a problem where set of feasible observations are provided by an expert and cost function is defined that characterizes which the dominate others hence, preferred. Our goal to find linear constraints would render all given while making preferred ones optimal for (objective) function. By doing so, we infer implicit region programming problem. Providing such regions (i) builds baseline ca...

In this paper we propose a simple model for the coupling behavior of the human spine for an inverse kinematics framework. Our spine model exhibits anatomically correct motions of the vertebrae of virtual mannequins by coupling standard swing and revolute joint models. The adjustement of the joints is made with several simple (in)equality constraints, resulting in a reduction of the solution spa...

We consider some inverse min-max (or max-min) network problems. Such an inverse problem is to modify the weights with bound constraints so that a given feasible solution becomes an optimal solution of a min-max (or max-min) network problem, and the deviation of the weights, measured by the weighted l1 norm or weighted l∞ norm, is minimum. In this paper, we present strongly polynomial time algor...

An inverse optimization problems is defined as follows: Let S denote the set of feasible solutions of an optimization problem P, let c be a specified cost vector, and xO be a given feasible solution. We want to perturb the cost vector c to d so that x is an optimal solution of P with respect to the cost vector d , and lid clip is minimum, where 11.llp denotes some selected Lp norm. In this pape...

In [1] the recursive inverse eigenvalue problem for matrices was introduced. In this paper we examine an open problem on the existence of symmetric positive semidefinite solutions that was posed there. We first give several counterexamples for the general case and then characterize under which further assumptions the conjecture is valid. 1. Introduction. In [1] several classes of recursive inve...

In this paper, we aim to solve an inverse robust optimization problem, in which the parameters in both the objective function and the robust constraint set need to be adjusted as little as possible so that a known feasible solution becomes the optimal one. We formulate this inverse problem as a minimization problem with a linear equality constraint, a second-order cone complementarity constrain...

Given an instance of the minimum cost flow problem, the corresponding inverse problem is to modify the arc costs as little as possible so that a given feasible flow becomes optimal to the modified minimum cost flow problem. In this article, we study this inverse problem in that the modifications are measured by the weighted bottleneck-type Hamming distance. We present a new efficient algorithm ...