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- Dorina Jibetean, Monique Laurent
- SIAM Journal on Optimization
- 2005

We consider the problem of minimizing a polynomial function on R n , known to be hard even for degree 4 polynomials. Therefore approximation algorithms are of interest. Lasserre [15] and Parrilo [23] have proposed approximating the minimum of the original problem using a hierarchy of lower bounds obtained via semidefinite programming relaxations. We propose… (More)

- Dorina Jibetean, Etienne de Klerk
- Math. Program.
- 2006

We consider the problem of global minimization of rational functions on IR n (unconstrained case), and on an open, connected, semi-algebraic subset of IR n , or the (partial) closure of such a set (constrained case). We show that in the univariate case (n = 1), these problems have exact reformulations as semidefinite programming (SDP) problems, by using… (More)

- Bernard Hanzon, Dorina Jibetean
- J. Global Optimization
- 2003

The problem of minimizing a polynomial function in several variables over R n is considered and an algorithm is given. When the polynomial has a minimum the algorithm returns the global minimum and nds at least one point in every connected component of the set of minimizers. A characterization of such points is given. When the polynomial does not have a… (More)

- ACADEMISCH PROEFSCHRIFT, Dorina Jibetean, B. Hanzon, Simona Orzan, Luc Habets, Anton Stoorvogel

A variety of problems in mathematical calculus can be solved by recursively applying a finite number of rules. Often, a generic solving strategy can be extracted and an interactive exercise system that emulates a tutor can be implemented. In this paper we show how software developed by us can be used to realize this interactivity. In particular, an… (More)

We consider here the problem of minimizing a polynomial function on R n. The problem is known to be hard even for degree 4. Therefore approximation algorithms are of interest. Lasserre [11] and Parrilo [16] have proposed approximating the minimum of the original problem using a hierarchy of lower bounds obtained via semidefi-nite programming relaxations. We… (More)

- Dorina Jibetean
- 2001

The paper deals with unconstrained global minimization of rational functions. A necessary condition is given for the function to have a nite innmum. In case the condition is satissed, the problem is shown to be equivalent to a speciic constrained polynomial optimization problem. In this paper, we solve a relaxation of the latter formulation using… (More)

In this paper we study unconstrained global optimization of rational functions. We give first few theoretical results and study then a relaxation of the initial problem. The relaxation is solved using LMI techniques. Therefore, in general our procedure will produce a lower bound of the infimum of the original problem. However, under no degeneracies, it is… (More)

- A. M. Cohen, H. Cuypers, +6 authors Dorina Jibetean
- 2005

This section deals with our work on interactive mathematical documents that make use of the World Wide Web. These documents take input from various sources, users, and mathematical services. Communication between these different entities can be realized using OpenMath. But, such communication and the interactivity inside the mathematical document take place… (More)

A state-space approach to H 2 model reduction of stable systems is pursued, using techniques from global rational optimization , and aimed at finding global optima. First, a concentrated version of the H 2 criterion is derived, by optimizing analytically with respect to a subset of parameters. Next, a bound is developed, which is shown to be sharp for… (More)