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Mardi 2 Décembre
| Heure: |
12:30 - 13:30 |
| Lieu: |
Salle B107, bâtiment B, Université de Villetaneuse |
| Résumé: |
Robust network design with uncertain outsourcing cost |
| Description: |
Michael Poss The expansion of a telecommunications network faces two sources of
uncertainty, which are the demand for traffic that shall transit through
the expanded network and the outsourcing cost that the network operator
will have to pay to handle the traffic that exceeds the capacity of its
network. The latter is determined by the future cost of
telecommunications services, whose negative correlation with the total
demand is empirically measured in the literature through the price
elasticity of demand. Unlike previous robust optimization works on the
subject, we consider in this paper both sources of uncertainty and the
correlation between them. The resulting mathematical model is a linear
program that exhibits a constraint with quadratic dependency on the
uncertainties. To solve the model, we propose a decomposition approach
that avoids considering the constraint for all scenarios. Instead, we
use a cutting plane algorithm that generates required scenarios on the
fly by solving linear multiplicative programs. Computational experiments
realized on the networks from SNDlib show that our approach is orders of
magnitude faster than the classical semidefinite programming
reformulation for such problems. |
Mardi 9 Décembre
| Heure: |
12:30 - 13:30 |
| Lieu: |
Salle B107, bâtiment B, Université de Villetaneuse |
| Résumé: |
Complexity aspects of graph convexities |
| Description: |
Mitre Dourado In the first half of the talk, I will survey the basic concepts, problems and main known results related to computational complexity aspects of graph convexities. In the second half, I will present some new results on the Radon number in the geodetic convexity, among them a polynomial time algorithm for finding the Radon number of unit interval graphs.
This is a joint work with:
Jayme Luiz Szwarcfiter
Alexandre Toman |
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