A survey of variants and extensions of the resource-constrained project scheduling problem <s> Networks for Multiple Projects <s> A zero-one 0-1 linear programming formulation of multiproject and job-shop scheduling problems is presented that is more general and computationally tractable than other known formulations. It can accommodate a wide range of real-world situations including multiple resource constraints, due dates, job splitting, resource, substitutability, and concurrency and nonconcurrency of job performance requirements. Three possible objective functions are discussed; minimizing total throughput time for all projects: minimizing the time by which all projects are completed i.e., minimizing makespan; and minimizing total lateness or lateness penalty for all projects. <s> BIB001 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Networks for Multiple Projects <s> Managing multiple projects is a complex task. It involves the integration of varieties of resources and schedules. The researchers have proposed many tools and techniques for single project scheduling. Mathematical programming and heuristics are limited in application. In recent years non-traditional techniques are attempted for scheduling. This paper proposes the use of a heuristic and a genetic algorithm for scheduling a multi-project environment with an objective to minimize the makespan of the projects. The proposed method is validated with numerical examples and is found competent. <s> BIB002 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Networks for Multiple Projects <s> We consider a multi-project scheduling problem, where each project is composed of a set of activities, with precedence relations, requiring specific amounts of local and shared (among projects) resources. The aim is to complete all the project activities, satisfying precedence and resource constraints, and minimizing each project schedule length. The decision making process is supposed to be decentralized, with as many local decision makers as the projects. A multi-agent system model, and an iterative combinatorial auction mechanism for the agent coordination are proposed. We provide a dynamic programming formulation for the combinatorial auction problem, and heuristic algorithms for both the combinatorial auction and the bidding process. An experimental analysis on the whole multi-agent system model is discussed. <s> BIB003 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Networks for Multiple Projects <s> Most approaches to multi-project scheduling are based on the assumption that resources can be transferred between projects without any expense in time and cost. As this assumption often is not realistic, we generalise the multi-project scheduling problem (RCMPSP) by additionally including transfer times and cost. To integrate this aspect, in a first step, we develop a framework for considering resource transfers in single and multi-project environments. It includes managerial approaches to handle resource transfers, a classification of resource transfer types and new roles that resources can take in these transfers. Afterwards, we define the multi-project scheduling problem with transfer times (RCMPSPTT) and formulate it in a basic and an extended version as integer linear programmes. Eventually, it is supplemented for the first time by cost considerations and introduced as resource constrained multi-project scheduling problem with transfer times and cost (RCMPSPTTC). Computational experiments compare the presented managerial approaches and prove the necessity of explicitly considering transfer times in project scheduling. Moreover, the experiments evaluate the presented MIP models and show that specialised solution procedures are vital. <s> BIB004 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Networks for Multiple Projects <s> The project scheduling problem involves the scheduling of project activities subject to precedence and/or resource constraints. Of obvious practical importance, it has been the subject of intensive research since the late fifties. A wide variety of commercialized project management software packages have been put to practical use. Despite all these efforts, numerous reports reveal that many projects escalate in time and budget and that many project scheduling procedures have not yet found their way to practical use. The objective of this paper is to confront project scheduling theory with project scheduling practice. We provide a generic hierarchical project planning and control framework that serves to position the various project planning procedures and discuss important research opportunities, the exploration of which may help to close the theory-practice gap. <s> BIB005
In practice, often not only one but several dependent projects have to be scheduled simultaneously. This is important if two or more projects which may be processed in parallel share at least one resource. Herroelen BIB005 stresses the importance of frameworks for scheduling multiple projects. The most common way to deal with multiple projects is to comprise their networks into a "super-network" by adding a "super-source" and a "super-sink," while a common pool of resources is considered. This approach has been proposed by Pritsker et al. BIB001 . Confessore et al. BIB003 consider a set of projects in which each project has its own resources while one additional resource is shared by the projects. The advantage of integrating multiple projects in a single network is that this provides a formal basis for the application of scheduling methods for single projects also to the case of multiple projects. As for the single-project case, further constraints can be added. Pritsker et al. BIB001 add due dates and deadlines for the sink activities of the single projects. Franck et al.  consider a network of multiple projects with minimal and maximal time lags. Krüger and Scholl BIB004 discuss a multi-project problem that includes resource transfers. Kumanan et al. BIB002 consider multiple projects the activities of which can be performed in one of several modes.