AI and OR approaches have complementary strengths: AI in domain-specific knowledge representation and OR in efficient mathemat:ical computation. Constraint Logic Programming (CLP), which combines these complementary strengths of the AI and OR approach, is introduced as a new tool to formalize a special class of constraint satisfaction problems that include both qualitative and quantitative cons...

Pivot-and-Fix, a new primal heuristic for finding feasible solutions for mixed integer programming (MIP) problems is presented in this paper. Pivot-and-Fixtries to explore potentially promising extreme points of the polyhedron of the problem and by forming smaller serach trees looks for integer feasible solutions. Computational results show that this heuristic could help MIP solvers to perform ...

The design of telecommunication network with capacity constraints of links, routers and ports of routers is considered in this paper. Specially, we limit each demand flow traversed through a pre-specified maximal number of links (called hops) under node failure scenarios in IP layer network. Such a design must be the most cost-effective and ensure that feasible flows continue to exist even when...

This paper presents a robust approach to solve Hoist Scheduling Problems (HSPs) based on an integration of Constraint Logic Programming (CLP) and Mixed Integer Programming (MIP). By contrast with previous dedicated models and algorithms for solving classes of HSPs, we deene only one model and run diierent solvers. The robust approach is achieved by using a CLP formalism. We show that our models...

MOTIVATION Assembling genomes from short read data has become increasingly popular, but the problem remains computationally challenging especially for larger genomes. We study the scaffolding phase of sequence assembly where preassembled contigs are ordered based on mate pair data. RESULTS We present MIP Scaffolder that divides the scaffolding problem into smaller subproblems and solves these...

We propose a mixed integer programming (MIP) model and iterative algorithms based on topological orders to solve optimization problems with acyclic constraints on a directed graph. The proposed MIP model has a significantly lower number of constraints compared to popular MIP models based on cycle elimination constraints and triangular inequalities. The proposed iterative algorithms use gradient...

hub covering problem (hlp) is a very popular areas of research for its wide ranges of applications in different service or manufacturing industries. this paper considers a bi-objective hub covering location problem with congestion. the objectives minimize the total transportation cost and the total waiting time for all hobs, respectively. the resulted multi-objective decision-making problem is ...

W describe a simple process for generating numerically safe cutting planes using floating-point arithmetic and the mixed-integer rounding procedure. Applying this method to the rows of the simplex tableau permits the generation of Gomory mixed-integer cuts that are guaranteed to be satisfied by all feasible solutions to a mixed-integer programming problem (MIP). We report on tests with the MIPL...

This paper considers a scheduling problem with component availability constraints in a supply chain consisting of two manufacturing facilities and a merge-in-transit facility. Three mixed-integer programming (MIP) models and a constraint programming (CP) model are compared in an extensive numerical study. Results show that when there are no components shared among the two manufacturers, the MIP...