A survey of variants and extensions of the resource-constrained project scheduling problem <s> Time-Switch Constraints <s> Crew or staff scheduling is a complex combinatorial problem. It consists of assigning tasks to persons which have to perform these task and to schedule the performance of the tasks. Railway and airline crew scheduling problems, audit scheduling problems, school and university course scheduling and staff scheduling in hospitals are typical examples of such combinatorial problems. <s> BIB001 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Time-Switch Constraints <s> The discrete time-cost trade-offs problem(DTCTP,for short) is a most widely concerned with bi-criteria optimization model in project scheduling literatures,which has been studied under three possible objectives.(1)P1:the so-called deadline problem involves the scheduling of project activities in order to minimize the total cost of the project while meeting a given deadline.(2)P2:the budget problem aims at minimizing the project duration without exceeding a given budget.(3)P3: the time/cost profile problem involves the generation of the complete efficient time-cost profile over the set of feasible project durations.However,the literature on the DTCTP with time-switch constraints are sparsely paid attention.In this paper,we firstly introduce the problem description of time-switch constraints,and then build the arithmetic model of the DTCTPTSC_-P2;From the point view of practicality,a genetic algorithm is developed to solve the model.Finally,a project example based on real-life situation is used to validate the model and the algorithm.At the same time,the results show that the model plays an instructional role for contractor to more closely control the project's scheduling. <s> BIB002
Time-switch constraints have been introduced by Yang and Chen  . The planning horizon is divided into cycles of work and rest time windows. An activity can start only in a work window. This approach allows to capture working times (e.g., working is allowed from Monday till Friday but not on weekends). Note that there is a certain relationship to the concept of forbidden periods (see Section 2.6), but a main difference is that the forbidden periods depend on the activities. Brucker and Knust BIB001 mention such time windows as well and point out that they can be taken into account by adding a renewable resource with a capacity of one during each work window and 0 otherwise. Vanhoucke et al. BIB002 employ time-switch constraints within a discrete time-cost tradeoff problem (see 2.5).