Authors:
Roni Levi
1
and
Sándor Danka
2
Affiliations:
1
Technion Israeli Institute of Technology, Israel
;
2
University of Pécs, Hungary
Keyword(s):
Project Scheduling, Resource-constrained Project, Resource-constrained Float, Heuristic Algorithm, Project Management.
Related
Ontology
Subjects/Areas/Topics:
Artificial Intelligence
;
Computational Intelligence
;
Evolution Strategies
;
Evolutionary Computing
;
Evolutionary Multiobjective Optimization
;
Hybrid Systems
;
Soft Computing
Abstract:
In this paper, we present a new unified theoretical model and the conception of the corresponding heuristic algorithm to solve several "what if" like float management problems in resource-constrained project scheduling. The traditional time-oriented resource-constrained project scheduling model for makespan minimization gives an optimal starting time set therefore an activity movement, may be able to destroy the resource-feasibility. The float management, as a stating base, needs a so-called forbidden-set oriented model (a forbidden-set oriented heuristic), which gives an optimal resource conflict repairing relation set. After inserting the additional predecessor-successor relations, in a optimal schedule every movable activity can be moved without destroying the resource feasibility. In the other side, when we have a forbidden-set oriented schedule, then according to the total free float, we have some freedom to redistribute the float among activities to answer several "what if" lik
e questions. For example, in the planning phase we can investigate the consequences of a delay or a longer duration which may be caused by a notorious element of the "critical" activity subset. The unified float management as a new tool was built into the forbidden-set oriented Sounds of Silence (SoS) metaheuristic frame (Csébfalvi et al., 2008a). From theoretical point of view, float management is invariant to the applied heuristic frame; therefore it can be built into any other heuristic which is developed to solve forbidden-set oriented resource-constrained project scheduling problem (RCPSP). The toolbox can be completed by any other new element (float measure), which can be described as a linear programming (LP) or a simple mixed integer linear programming (MILP) problem on the set of the forbidden-set oriented (freely movable without resource-conflicts) solutions as a problem-specific redistribution of the total free float of the project. The essence and viability of our unified approach is illustrated by a set of examples.
(More)