Results 1  10
of
30
Complete search in continuous global optimization and constraint satisfaction
 ACTA NUMERICA 13
, 2004
"... ..."
A Constraint Programming Approach to the Hospitals / Residents Problem
 IN WORKSHOP ON MODELLING AND REFORMULATING CONSTRAINT SATISFACTION PROBLEMS AT CP’05
, 2005
"... An instance I of the Hospitals / Residents problem (HR) involves a set of residents (graduating medical students) and a set of hospitals, where each hospital has a given capacity. The residents have preferences for the hospitals, as do hospitals for residents. A solution of I is a stable matching, w ..."
Abstract

Cited by 7 (4 self)
 Add to MetaCart
(Show Context)
An instance I of the Hospitals / Residents problem (HR) involves a set of residents (graduating medical students) and a set of hospitals, where each hospital has a given capacity. The residents have preferences for the hospitals, as do hospitals for residents. A solution of I is a stable matching, which is an assignment of residents to hospitals that respects the capacity conditions and preference lists in a precise way. In this paper we present constraint encodings for HR that give rise to important structural properties. We also present a computational study using both randomlygenerated and realworld instances. Our study suggests that Constraint Programming is indeed an applicable technology for solving this problem, in terms of both theory and practice.
A specialised binary constraint for the stable marriage problem
 In SARA 2005
, 2005
"... Abstract. We present a specialised binary constraint for the stable marriage problem. This constraint acts between a pair of integer variables where the domains of those variables represent preferences. Our constraint enforces stability and disallows bigamy. For a stable marriage instance with n men ..."
Abstract

Cited by 5 (4 self)
 Add to MetaCart
(Show Context)
Abstract. We present a specialised binary constraint for the stable marriage problem. This constraint acts between a pair of integer variables where the domains of those variables represent preferences. Our constraint enforces stability and disallows bigamy. For a stable marriage instance with n men and women we require n 2 of these constraints, and the complexity of enforcing arcconsistency is O(n 3). Although this is nonoptimal, empirical evidence suggests that in practical terms our encoding significantly outperforms the optimal encoding given in [7] in both space and time. 1
Comparison of Symmetry Breaking Methods in Constraint Programming
 In proceedings of SymCon05, the 5th International Workshop on Symmetry in Constraints
, 2005
"... Symmetry in a Constraint Satisfaction Problem can cause wasted search, which can be avoided by adding constraints to the CSP to exclude symmetric assignments or by modifying the search algorithm so that search never visits assignments symmetric to those already considered. One such approach is SBDS ..."
Abstract

Cited by 5 (1 self)
 Add to MetaCart
Symmetry in a Constraint Satisfaction Problem can cause wasted search, which can be avoided by adding constraints to the CSP to exclude symmetric assignments or by modifying the search algorithm so that search never visits assignments symmetric to those already considered. One such approach is SBDS (Symmetry Breaking During Search); a modification is GAPSBDS, which works with the symmetry group rather than individual symmetries. There has been little experience of how these techniques compare in practice. We compare their performance in finding all graceful labellings of graphs with symmetry. For these problems, GAPSBDS is faster than SBDS unless there are few symmetries. When simple symmetrybreaking constraints can be found to break all the symmetry, GAPSBDS is slower; if the constraints break only part of the symmetry, GAPSBDS does less search and is faster. Eliminating symmetry has allowed us to find all graceful labellings, or prove that there are none, for several graphs whose gracefulness was not previously known. 1
Reconfigurable Asynchronous Logic Automata (RALA)
"... Computer science has served to insulate programs and programmers from knowledge of the underlying mechanisms used to manipulate information, however this fiction is increasingly hard to maintain as computing devices decrease in size and systems increase in complexity. Manifestations of these limits ..."
Abstract

Cited by 4 (4 self)
 Add to MetaCart
(Show Context)
Computer science has served to insulate programs and programmers from knowledge of the underlying mechanisms used to manipulate information, however this fiction is increasingly hard to maintain as computing devices decrease in size and systems increase in complexity. Manifestations of these limits appearing in computers include scaling issues in interconnect, dissipation, and coding. Reconfigurable Asynchronous Logic Automata (RALA) is an alternative formulation of computation that seeks to align logical and physical descriptions by exposing rather than hiding this underlying reality. Instead of physical units being represented in computer programs only as abstract symbols, RALA is based on a lattice of cells that asynchronously pass state tokens corresponding to physical resources. We introduce the design of RALA, review its relationships to its many progenitors, and discuss its benefits,
Exploiting sensor spatial redundancy to improve network lifetime
 in IEEE Global Telecommunications Conference (Globecom), 2004
"... Abstract — One of the most critical issues in wireless sensor networks is represented by the limited availability of energy within network nodes; thus, making good use of energy is a must to increase network lifetime. We define as network lifetime the period from the time instant when the network st ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
Abstract — One of the most critical issues in wireless sensor networks is represented by the limited availability of energy within network nodes; thus, making good use of energy is a must to increase network lifetime. We define as network lifetime the period from the time instant when the network starts functioning till the network runs satisfying its quality requirements, i.e., a given level of coverage in the area of interest is guaranteed. To maximize system lifetime, we exploit sensor spatial redundancy by defining subsets of sensors active in different time period, to allow sensors to save energy when inactive. Two approaches are presented: the first one, based on mathematical programming techniques, must run in a centralized way, whereas the second one is based on a greedy algorithm aiming at a distributed implementation. To asses their performance and provide guidance to network design, the two approaches are compared by varying several network parameters. I.
Computing Replenishment Cycle Policy under Nonstationary Stochastic Lead Time
, 2008
"... In this paper we address the general multiperiod production/inventory problem with nonstationary stochastic demand and supplier lead time under servicelevel constraints. A replenishment cycle policy (R n,S n) is modeled, where R n is the nth replenishment cycle length and S n is the respective o ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
In this paper we address the general multiperiod production/inventory problem with nonstationary stochastic demand and supplier lead time under servicelevel constraints. A replenishment cycle policy (R n,S n) is modeled, where R n is the nth replenishment cycle length and S n is the respective orderuptolevel. Initially we extend an existing formulation for this policy in a way to incorporate a dynamic deterministic lead time with the assumption of order crossover. Following this, we extend the model to incorporate a nonstationary stochastic lead time. Within a constraint programming framework, a dedicated constraint implementing a hybrid approach is proposed to compute replenishment cycle policy parameters.
Optimisation of Forest Road Investments and the Roundwood Supply
"... Olsson.L. 2004. Optimisation of forest road investments and the roundwood supply chain. ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
(Show Context)
Olsson.L. 2004. Optimisation of forest road investments and the roundwood supply chain.