Results 1 
5 of
5
A Polynomially Searchable Exponential Neighbourhood for Graph Colouring
, 1998
"... This paper presents a new neighbourhood structure for Graph Colouring problems based upon permutations of the colours of vertices in a subgraph. This neighbourhood is an exponentially large subspace of the solution space, for which a local optimum can be found in polynomial time using an algorit ..."
Abstract

Cited by 10 (1 self)
 Add to MetaCart
This paper presents a new neighbourhood structure for Graph Colouring problems based upon permutations of the colours of vertices in a subgraph. This neighbourhood is an exponentially large subspace of the solution space, for which a local optimum can be found in polynomial time using an algorithm called Permutation Descent. We thus provide
Idwalk : A candidate list strategy with a simple diversification device
 CP 2004: Lecture Notes in Computer Science
, 2004
"... Abstract. This paper presents a new optimization metaheuristic called ID Walk (Intensification/Diversification Walk) that offers advantages for combining simplicity with effectiveness. In addition to the number S of moves, ID Walk uses only one parameter Max which is the maximum number of candidate ..."
Abstract

Cited by 9 (4 self)
 Add to MetaCart
(Show Context)
Abstract. This paper presents a new optimization metaheuristic called ID Walk (Intensification/Diversification Walk) that offers advantages for combining simplicity with effectiveness. In addition to the number S of moves, ID Walk uses only one parameter Max which is the maximum number of candidate neighbors studied in every move. This candidate list strategy manages the Max candidates so as to obtain a good tradeoff between intensification and diversification. A procedure has also been designed to tune the parameters automatically. We made experiments on several hard combinatorial optimization problems, and ID Walk compares favorably with correspondingly simple instances of leading metaheuristics, notably tabu search, simulated annealing and Metropolis. Thus, among algorithmic variants that are designed to be easy to program and implement, ID Walk has the potential to become an interesting alternative to such recognized approaches. Our automatic tuning tool has also allowed us to compare several variants of ID Walk and tabu search to analyze which devices (parameters) have the greatest impact on the computation time. A surprising result shows that the specific diversification mechanism embedded in ID Walk is very significant, which motivates examination of additional instances in this new class of “dynamic ” candidate list strategies. 1
The Network Packing Problem in Terrestrial Broadcasting
, 2003
"... The introduction of digital terrestrial broadcasting all over Europe requires a complete and challenging replanning of inplace analog systems. But an abrupt migration of resources (transmitters and frequencies) from analog to digital networks cannot be accomplished, since the analog services must ..."
Abstract

Cited by 3 (1 self)
 Add to MetaCart
(Show Context)
The introduction of digital terrestrial broadcasting all over Europe requires a complete and challenging replanning of inplace analog systems. But an abrupt migration of resources (transmitters and frequencies) from analog to digital networks cannot be accomplished, since the analog services must be preserved temporarily. Hence, a multinetwork, multiobjective, problem arises, referred to as the Network Packing Problem, in which several networks, both analog and digital, sharing a common set of resources, have to be designed. In Italy this problem is particularly challenging, because of a large number of transmitters, orographical features and strict requirements imposed by Italian law. In this paper we report our experience developing solution methods at the major Italian broadcaster Radiotelevisione Italiana (RAI S.p.A.). We propose a twostage heuristic. In the ¯rst stage emission powers are assigned to each network separately. In the second stage frequencies are assigned to all networks so as to minimize the loss from mutual interference. A software tool incorporating our methodology is currently in use at RAI to help discover and select highquality alternatives for the deployment of digital equipment.
The independent set problem and the thinness of a graph
 OPERATIONS RESEARCH LETTERS
"... We introduce a polytime algorithm for the maximum weighted stable set problem, when a certain representation is given for a graph. The algorithm generalizes the algorithm for interval graphs and that for graphs with bounded pathwidth. By a suitable application to the frequency assignment problem, w ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
We introduce a polytime algorithm for the maximum weighted stable set problem, when a certain representation is given for a graph. The algorithm generalizes the algorithm for interval graphs and that for graphs with bounded pathwidth. By a suitable application to the frequency assignment problem, we find better solutions for almost all the instances of a relevant testbed.
Solving stability problems on a superclass of interval graphs
"... We introduce a graph invariant, called thinness, and show that a maximum weighted stable set on a graph G(V;E) with thinness k may be found in O( jV j ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
(Show Context)
We introduce a graph invariant, called thinness, and show that a maximum weighted stable set on a graph G(V;E) with thinness k may be found in O( jV j