A schedule or a timetable , as a basic time-management tool, consists of a list of times at which possible tasks , events, or actions are intended to take place, or of a sequence of events in the chronological order in which such things are intended to take place. The process of creating a schedule — deciding how to order these tasks and how to commit resources between the variety of possible tasks — is called scheduling , and a person responsible for making a particular schedule may be called a scheduler . Making and following schedules is an ancient human activity.
31-402: A travel itinerary is a schedule of events relating to planned travel , generally including destinations to be visited at specified times and means of transportation to move between those destinations. For example, both the plan of a business trip and the route of a road trip , or the proposed outline of one, are travel itineraries. The construction of a travel itinerary may be assisted by
62-486: A domino effect that can negatively impact the entire area's transportation planning. In an educational institution, a timetable must be established that refers students and teachers to classrooms each hour. The challenge of constructing this schedule for larger institutions was addressed by Gunther Schmidt and Thomas Ströhlein in 1976. They formalized the timetable construction problem, and indicated an iterative process using logical matrices and hypergraphs to obtain
93-566: A set of goals within a set time. Schedules can usefully span both short periods, such as a daily or weekly schedule, and long-term planning for periods of several months or years. They are often made using a calendar , where the person making the schedule can note the dates and times at which various events are planned to occur. Schedules that do not set forth specific times for events to occur may instead list algorithmically an expected order in which events either can or must take place. In some situations, schedules can be uncertain, such as where
124-427: A solution. Gantt chart A Gantt chart is a bar chart that illustrates a project schedule . It was designed and popularized by Henry Gantt around the years 1910–1915. Modern Gantt charts also show the dependency relationships between activities and the current schedule status. A Gantt chart is a type of bar chart that illustrates a project schedule. This chart lists the tasks to be performed on
155-404: A traveller, who can then pick one that they're most satisfied with. However, with the advent of the internet, online maps, navigation, online trip planners and easier access to travel information in general, travellers, especially the younger ones prefer a more do-it-yourself approach to travel planning. Since a travel itinerary might serve different purposes for different kinds of travellers, it
186-433: A truck before loading materials on the truck (since nothing can be loaded until the truck is available for things to be loaded on). Scheduling of projects, therefore, requires the identification of all of the tasks necessary to complete the project, and the earliest time at which each task can be completed. In creating a schedule, a certain amount of time is usually set aside as a contingency against unforeseen days. This time
217-464: A vertical "TODAY" line. Gantt charts are sometimes equated with bar charts. Gantt charts are usually created initially using an early start time approach , where each task is scheduled to start immediately when its prerequisites are complete. This method maximizes the float time available for all tasks. Widely used in project planning in the present day, Gantt charts were considered revolutionary when introduced. The first known tool of this type
248-407: Is a schedule that is only of importance to the people who must directly abide by it. It has been noted that "groups often begin with a schedule imposed from the outside, but effective groups also develop an internal schedule that sets goals for the completion of micro-tasks". Unlike schedules for public events or publicly available amenities, there is no need to go to the time and effort of publicizing
279-429: Is called scheduling variance, or float , and is a core concept for the critical path method . Scheduling is important as an internal process in computer science , wherein a database transaction schedule is a list of actions from a set of transactions in databases, and scheduling is the way various processes are assigned in computer multitasking and multiprocessing operating system design. This kind of scheduling
310-576: Is concerned with scheduling a number of employees with typical constraints such as rotation of shifts, limits on overtime, etc. The travelling salesman problem is concerned with scheduling a series of journeys to minimize time or distance. Some of these problems may be solved efficiently with linear programming , but many scheduling problems require integer variables. Although efficient algorithms exist to give integer solutions in some situations (see network flow models), most problems that require integer solutions cannot yet be solved efficiently. Scheduling
341-424: Is crucial for a travel agent to know all the characteristics of her/his target of customers. A typical business traveller's itinerary might include information about meetings, events and contacts with some time for leisure travel, efficiently. When a proposed itinerary has been finalised, the details need to be entered into an airline reservation system , where the appropriate reservations and bookings are made. In
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#1732775673522372-414: Is desirable to schedule the usage of wireless resources as efficiently as possible, while maximizing the overall network performance. The scheduling of resources, usually subject to constraints, is the subject of several problems that are in the area of research known as operations research , usually in terms of finding an optimal solution or method for solving. For example, the nurse scheduling problem
403-412: Is drawn at the time index when the progress Gantt chart is created, and this line can then be compared with shaded tasks. If everything is on schedule, all task portions left of the line will be shaded, and all task portions right of the line will not be shaded. This provides a visual representation of how the project and its tasks are ahead or behind schedule. Linked Gantt charts contain lines indicating
434-413: Is estimated using the beta probability distribution for the time estimates, using the formula ( O + 4 M + P ) ÷ 6. Once this step is complete, one can draw a Gantt chart or a network diagram. In a progress Gantt chart, tasks are shaded in proportion to the degree of their completion: a task that is 60% complete would be 60% shaded, starting from the left. A vertical line
465-581: Is incorporated into the computer program, and the user may be completely unaware of what tasks are being carried out and when. Scheduling operations and issues in computing may include: Wireless networks should have a flexible service architecture to integrate different types of services on a single air-interface because terminals have different service requirements. On top of the flexible service architecture, effective quality of service (QoS) management schemes are also needed. Therefore, wireless resources need to be shared among all terminals carefully and it
496-541: Is useful in transportation planning . The important components of transportation improvement proposals include (a) comprehensive evaluations of the scope of work to be completed, (b) reasonably accurate cost estimates for finishing the task, and (c) a feasible project schedule. If any of these factors are not accurately defined, then there is a strong possibility of unexpected difficulties. Poor scoping and/or scheduling may result in serious budget problems, delays and cancellations of transportation improvements, and sometimes even
527-675: The Soviet Union in 1929 when he was working for the Supreme Soviet of the National Economy . They were used in developing the First Five Year Plan , supplying Russian translations to explain their use. In the 1980s, personal computers allowed widespread creation of complex and elaborate Gantt charts. The first desktop applications were intended mainly for project managers and project schedulers. With
558-484: The advent of the Internet and increased collaboration over networks at the end of the 1990s, Gantt charts became a common feature of web-based applications, including collaborative groupware . By 2012, almost all Gantt charts were made by software which can easily adjust to schedule changes. In 1999, Gantt charts were identified as "one of the most widely used management tools for project scheduling and control". In
589-460: The completion of a project with which the public has no interaction public prior to its completion. In project management , a formal schedule will often be created as an initial step in carrying out a specific project, such as the construction of a building, development of a product, or launch of a program. Establishing a project management schedule involves listing milestones, activities, and deliverables with intended start and finish dates, of which
620-470: The conduct of daily life relies on environmental factors outside human control. People who are vacationing or otherwise seeking to reduce stress and achieve relaxation may intentionally avoid having a schedule for a certain period of time. Certain kinds of schedules reflect information that is generally made available to the public, so that members of the public can plan certain activities around them. These may include things like: An internal schedule
651-605: The dependencies between tasks. However, linked Gantt charts quickly become cluttered in all but the simplest cases. Critical path network diagrams are superior to visually communicate the relationships between tasks. Nevertheless, Gantt charts are often preferred over network diagrams because Gantt charts are easily interpreted without training, whereas critical path diagrams require training to interpret. Gantt chart software typically provides mechanisms to link task dependencies, although this data may or may not be visually represented. Gantt charts and network diagrams are often used for
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#1732775673522682-521: The first major applications of Gantt charts was by the United States during World War I , at the instigation of General William Crozier . The earliest Gantt charts were drawn on paper and therefore had to be redrawn entirely in order to adjust to schedule changes. For many years, project managers used pieces of paper or blocks for Gantt chart bars so they could be adjusted as needed. Gantt's collaborator Walter Polakov introduced Gantt charts to
713-440: The following tables there are seven tasks, labeled a through g . Some tasks can be done concurrently ( a and b ) while others cannot be done until their predecessor task is complete ( c and d cannot begin until a is complete). Additionally, each task has three time estimates: the optimistic time estimate ( O ), the most likely or normal time estimate ( M ), and the pessimistic time estimate ( P ). The expected time ( T E )
744-450: The industry, the travel plan is commonly known as the itinerary and the data on the reservation system is known as a passenger name record (PNR). Schedule Some scenarios associate this kind of planning with learning life skills . Schedules are necessary, or at least useful, in situations where individuals need to know what time they must be at a specific location to receive a specific service, and where people need to accomplish
775-402: The internal schedule. To the contrary, an internal schedule may be kept confidential as a matter of security or propriety. An example of an internal schedule is a workplace schedule , which lists the hours that specific employees are expected to be in a workplace, ensure sufficient staffing at all times while in some instances avoiding overstaffing. A work schedule for a business that is open to
806-463: The public must correspond to the hours of operation of the business, so that employees are available at times when customers are able to use the services of the business. One common method of scheduling employees to ensure the availability of appropriate resources is a Gantt chart . Another example of an internal schedule is the class schedule of an individual student, indicating what days and times their classes will be held. A schedule may also involve
837-491: The scheduling of employees may be an element. A production process schedule is used for the planning of the production or the operation, while a resource schedule aids in the logistical planning for sharing resources among several entities. In such cases, a schedule "is obtained by estimating the duration of each task and noting any dependencies amongst those tasks". Dependencies , in turn, are tasks that must be completed in order to make other tasks possible, such as renting
868-715: The time; however, the prior development leading to Schürch's work is unclear. Unlike later Gantt charts, Schürch's charts did not display interdependencies, leaving them to be inferred by the reader. These were also static representations of a planned schedule. The chart is named after Henry Gantt (1861–1919), who designed his chart around the years 1910–1915. Gantt originally created his tool for systematic, routine operations. He designed this visualization tool to more easily measure productivity levels of employees and gauge which employees were under- or over-performing. Gantt also frequently included graphics and other visual indicators in his charts to track performance. One of
899-442: The use of travel literature , including travel journals and diaries, a guide book containing information for visitors or tourists about the destination, or a trip planner website dedicated to helping the users plan their trips. Typically a travel itinerary is prepared by a travel agent who assists one in conducting their travel for business or leisure. Most commonly a travel agent provides a list of pre-planned travel itineraries to
930-560: The vertical axis, and time intervals on the horizontal axis. The width of the horizontal bars in the graph shows the duration of each activity. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project . Terminal elements and summary elements constitute the work breakdown structure of the project. Modern Gantt charts also show the dependency (i.e., precedence network) relationships between activities. Gantt charts can be used to show current schedule status using percent-complete shadings and
961-550: Was developed in 1896 by Karol Adamiecki , who called it a harmonogram . Adamiecki, however, published his chart only in Russian and Polish which limited both its adoption and recognition of his authorship. In 1912, Hermann Schürch [ de ] published what could be considered Gantt charts while discussing a construction project. Charts of the type published by Schürch appear to have been in common use in Germany at