Project Management Body of Knowledge
The Project Management Body of Knowledge is a set of standard terminology and guidelines for project management. The body of knowledge evolves over time and is presented in A Guide to the Project Management Body of Knowledge, a book whose sixth edition was released in 2017; the Guide is a document resulting from work overseen by the Project Management Institute, which offers the CAPM and PMP certifications. Much of the PMBOK Guide is unique to project management e.g. critical path method and work breakdown structure. The PMBOK Guide overlaps with general management regarding planning, staffing and controlling the operations of an organisation. Other management disciplines which overlap with the PMBOK Guide include financial forecasting, organisational behaviour, management science and other planning methods. Earlier versions of the PMBOK Guide were recognized as standards by the American National Standards Institute which assigns standards in the United States and the Institute of Electrical and Electronics Engineers.
The evolution of the PMBOK Guide is reflected in editions of the Guide. The Guide was first published by the Project Management Institute in 1996; that document was to some extent based on earlier work that began with a white paper published in 1983 called the "Ethics and Accreditation Committee Final Report." The second edition was published in 2000. In 2004, the PMBOK Guide — Third Edition was published with major changes from the previous editions; the Fourth edition was published in 2008. The Fifth Edition was released in 2013; the latest English-language version of The PMBOK Guide — The Sixth Edition was released in September 2017. The PMBOK Guide is intended to be a "subset of the project management body of knowledge, recognized as a good practice.'Generally recognized' means the knowledge and practices described are applicable to most projects most of the time and there is a consensus about their value and usefulness.'Good practice' means there is a general agreement that the application of the knowledge, skills and techniques can enhance the chance of success over many projects."
This means that sometimes the "latest" project management trends promoted by consultants, may not be part of the latest version of The PMBOK Guide. However, the 6th Edition of the PMBOK Guide now includes an "Agile Practice Guide" The PMBOK Guide is process-based, meaning it describes work as being accomplished by processes; this approach is consistent with other management standards such as ISO 9000 and the Software Engineering Institute's CMMI. Processes interact throughout a project or its various phases. Inputs Tools and Techniques Outputs A Guide to the Project Management Body of Knowledge — Sixth Edition provides guidelines for managing individual projects and defines project management related concepts, it describes the project management life cycle and its related processes, as well as the project life cycle. And for the first time it includes an "Agile Practice Guide"; the PMBOK as described in the Guide recognizes 49 processes that fall into five basic process groups and ten knowledge areas that are typical of most projects, most of the time.
The five process groups are: Initiating: processes performed to define a new project or a new phase of an existing project by obtaining authorization to start the project or phase. Planning: Those processes required to establish the scope of the project, refine the objectives, define the course of action required to attain the objectives that the project was undertaken to achieve. Executing: Those processes performed to complete the work defined in the project management plan to satisfy the project specifications Monitoring and Controlling: Those processes required to track and regulate the progress and performance of the project. Closing: Those processes performed to finalize all activities across all Process Groups to formally close the project or phase; the ten knowledge areas, each of which contains some or all of the project management processes, are: Project Integration Management: the processes and activities needed to identify, combine and coordinate the various processes and project management activities within the project management process groups.
Project Scope management: the processes required to ensure that the project includes all the work required, only the work required, to complete the project successfully. Project Schedule Management: the processes required to manage the timely completion of the project; until the 6th edition of the PMBOK Guide this was called "Project Time Management" Project Cost Management: the processes involved in planning, budgeting, funding and controlling costs so that the project can be completed within the approved budget. Project Quality Management: the processes and activities of the performing organization that determine quality policies and responsibilities so that the project will satisfy the needs for which it was undertaken. Project Resource Management: the processes that organize and lead the project team; until the 6th edition of the PMBOK Guide this was called "Project Human Resource Management" Project Communications Management: the processes that are required to ensure timely and appropriate planning, creation, storage, management, control and the ultimate disposition of project information.
Project Risk Management: the pr
Program evaluation and review technique
The program evaluation and review technique is a statistical tool used in project management, designed to analyze and represent the tasks involved in completing a given project. First developed by the United States Navy in the 1950s, it is used in conjunction with the critical path method. PERT is a method of analyzing the tasks involved in completing a given project the time needed to complete each task, to identify the minimum time needed to complete the total project, it incorporates uncertainty by making it possible to schedule a project while not knowing the details and durations of all the activities. It is more of an event-oriented technique rather than start- and completion-oriented, is used more in projects where time is the major factor rather than cost, it is applied to large-scale, one-time, non-routine infrastructure and Research and Development projects. Program Evaluation Review Technique offers a management tool, which relies "on arrow and node diagrams of activities and events: arrows represent the activities or work necessary to reach the events or nodes that indicate each completed phase of the total project."PERT and CPM are complementary tools, because "CPM employs one time estimate and one cost estimate for each activity.
Although these are distinct differences, the term PERT is applied to all critical path scheduling." "PERT" was developed to simplify the planning and scheduling of large and complex projects. It was developed for the U. S. Navy Special Projects Office in 1957 to support the U. S. Navy's Polaris nuclear submarine project, it found applications all over industry. An early example was it was used for the 1968 Winter Olympics in Grenoble which applied PERT from 1965 until the opening of the 1968 Games; this project model was the first of its kind, a revival for scientific management, founded by Frederick Taylor and refined by Henry Ford. DuPont's critical path method was invented at the same time as PERT. PERT stood for Program Evaluation Research Task, but by 1959 was renamed, it had been made public in 1958 in two publications of the U. S. Department of the Navy, entitled Program Evaluation Research Task, Summary Report, Phase 1. and Phase 2. In a 1959 article in The American Statistician the main Willard Fazar, Head of the Program Evaluation Branch, Special Projects Office, U.
S. Navy, gave a detailed description of the main concepts of the PERT, he explained: Through an electronic computer, the PERT technique processes data representing the major, finite accomplishments essential to achieve end-objectives. Such time expectations include estimates of "most time", "optimistic time", "pessimistic time" for each activity; the technique is a management control tool. The concept of PERT was developed by an operations research team staffed with representatives from the Operations Research Department of Booz Allen Hamilton. Ten years after the introduction of PERT in 1958 the American librarian Maribeth Brennan published a selected bibliography with about 150 publications on PERT and CPM, published between 1958 and 1968; the origin and development was summarized as follows: PERT originated in 1958 with the... Polaris missile construction scheduling. Since that time, it has been used extensively not only by the aerospace industry but in many situations where management desires to achieve an objective or complete a task within a scheduled time and cost expenditure.
PERT and CPM may be calculated manually or with a computer, but they require major computer support for detailed projects. A number of colleges and universities now offer instructional courses in both. For the subdivision of work units in PERT another tool was developed: the Work Breakdown Structure; the Work Breakdown Structure provides "a framework for complete networking, the Work Breakdown Structure was formally introduced as the first item of analysis in carrying out basic PERT/COST." In a PERT diagram, the main building block is the event, with connections to its known predecessor events and successor events. PERT event: a point that marks the start or completion of one or more activities, it uses no resources. When it marks the completion of one or more activities, it is not "reached" until all of the activities leading to that event have been completed. Predecessor event: an event that precedes some other event without any other events intervening. An event can be the predecessor of multiple events.
Successor event: an event that follows some other event without any other intervening events. An event can be the successor of multiple events. Besides events, PERT knows activities an
Systems engineering
Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking principles to organize this body of knowledge; the individual outcome of such efforts, an engineered system, can be defined as a combination of components that work in synergy to collectively perform a useful function. Issues such as requirements engineering, logistics, coordination of different teams and evaluation, maintainability and many other disciplines necessary for successful system development, design and ultimate decommission become more difficult when dealing with large or complex projects. Systems engineering deals with work-processes, optimization methods, risk management tools in such projects, it overlaps technical and human-centered disciplines such as industrial engineering, mechanical engineering, manufacturing engineering, control engineering, software engineering, electrical engineering, organizational studies, civil engineering and project management.
Systems engineering ensures that all aspects of a project or system are considered, integrated into a whole. The systems engineering process is a discovery process, quite unlike a manufacturing process. A manufacturing process is focused on repetitive activities that achieve high quality outputs with minimum cost and time; the systems engineering process must begin by discovering the real problems that need to be resolved, identifying the most probable or highest impact failures that can occur – systems engineering involves finding solutions to these problems. The term systems engineering can be traced back to Bell Telephone Laboratories in the 1940s; the need to identify and manipulate the properties of a system as a whole, which in complex engineering projects may differ from the sum of the parts' properties, motivated various industries those developing systems for the U. S. Military; when it was no longer possible to rely on design evolution to improve upon a system and the existing tools were not sufficient to meet growing demands, new methods began to be developed that addressed the complexity directly.
The continuing evolution of systems engineering comprises the development and identification of new methods and modeling techniques. These methods aid in a better comprehension of the design and developmental control of engineering systems as they grow more complex. Popular tools that are used in the systems engineering context were developed during these times, including USL, UML, QFD, IDEF0. In 1990, a professional society for systems engineering, the National Council on Systems Engineering, was founded by representatives from a number of U. S. corporations and organizations. NCOSE was created to address the need for improvements in systems engineering practices and education; as a result of growing involvement from systems engineers outside of the U. S. the name of the organization was changed to the International Council on Systems Engineering in 1995. Schools in several countries offer graduate programs in systems engineering, continuing education options are available for practicing engineers.
Systems engineering signifies only an approach and, more a discipline in engineering. The aim of education in systems engineering is to formalize various approaches and in doing so, identify new methods and research opportunities similar to that which occurs in other fields of engineering; as an approach, systems engineering is interdisciplinary in flavour. The traditional scope of engineering embraces the conception, development and operation of physical systems. Systems engineering, as conceived, falls within this scope. "Systems engineering", in this sense of the term, refers to the building of engineering concepts. The use of the term "systems engineer" has evolved over time to embrace a wider, more holistic concept of "systems" and of engineering processes; this evolution of the definition has been a subject of ongoing controversy, the term continues to apply to both the narrower and broader scope. Traditional systems engineering was seen as a branch of engineering in the classical sense, that is, as applied only to physical systems, such as spacecraft and aircraft.
More systems engineering has evolved to a take on a broader meaning when humans were seen as an essential component of a system. Checkland, for example, captures the broader meaning of systems engineering by stating that'engineering' "can be read in its general sense. Enterprise Systems Engineering pertains to the view of enterprises, that is, organizations or combinations of organizations, as systems. Service Systems Engineering has to do with the engineering of service systems. Checkland defines a service system as a system, conceived as serving another system. Most civil infrastructure systems are service systems. Systems engineering focuses on analyzing and eliciting customer needs and required functionality early in the development cycle, documenting requirements proceeding with design synthesis and system validation while considering the complete problem, the system lifecycle; this includes understanding all of the stakeholders involved. Oliver et al. claim that the systems engineerin
NASA
The National Aeronautics and Space Administration is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research. NASA was established in 1958; the new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles; the agency is responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA science is focused on better understanding Earth through the Earth Observing System. From 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1.
In the early 1950s, there was challenge to launch an artificial satellite for the International Geophysical Year. An effort for this was the American Project Vanguard. After the Soviet launch of the world's first artificial satellite on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts; the US Congress, alarmed by the perceived threat to national security and technological leadership, urged immediate and swift action. On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever. On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology" stating: It is of great urgency and importance to our country both from consideration of our prestige as a nation as well as military necessity that this challenge be met by an energetic program of research and development for the conquest of space... It is accordingly proposed that the scientific research be the responsibility of a national civilian agency...
NACA is capable, by rapid extension and expansion of its effort, of providing leadership in space technology. While this new federal agency would conduct all non-military space activity, the Advanced Research Projects Agency was created in February 1958 to develop space technology for military application. On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA; when it began operations on October 1, 1958, NASA absorbed the 43-year-old NACA intact. A NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA. A significant contributor to NASA's entry into the Space Race with the Soviet Union was the technology from the German rocket program led by Wernher von Braun, now working for the Army Ballistic Missile Agency, which in turn incorporated the technology of American scientist Robert Goddard's earlier works. Earlier research efforts within the US Air Force and many of ARPA's early space programs were transferred to NASA.
In December 1958, NASA gained control of the Jet Propulsion Laboratory, a contractor facility operated by the California Institute of Technology. The agency's leader, NASA's administrator, is nominated by the President of the United States subject to approval of the US Senate, reports to him or her and serves as senior space science advisor. Though space exploration is ostensibly non-partisan, the appointee is associated with the President's political party, a new administrator is chosen when the Presidency changes parties; the only exceptions to this have been: Democrat Thomas O. Paine, acting administrator under Democrat Lyndon B. Johnson, stayed on while Republican Richard Nixon tried but failed to get one of his own choices to accept the job. Paine was confirmed by the Senate in March 1969 and served through September 1970. Republican James C. Fletcher, appointed by Nixon and confirmed in April 1971, stayed through May 1977 into the term of Democrat Jimmy Carter. Daniel Goldin was appointed by Republican George H. W. Bush and stayed through the entire administration of Democrat Bill Clinton.
Robert M. Lightfoot, Jr. associate administrator under Democrat Barack Obama, was kept on as acting administrator by Republican Donald Trump until Trump's own choice Jim Bridenstine, was confirmed in April 2018. Though the agency is independent, the survival or discontinuation of projects can depend directly on the will of the President; the first administrator was Dr. T. Keith Glennan appointed by Republican President Dwight D. Eisenhower. During his term he brought together the disparate projects in American space development research; the second administrator, James E. Webb, appointed by President John F. Kennedy, was a Democrat who first publicly served under President Harry S. Truman. In order to implement the Apollo program to achieve Kennedy's Moon la
Work breakdown structure
A work-breakdown structure in project management and systems engineering, is a deliverable-oriented breakdown of a project into smaller components. A work breakdown structure is a key project deliverable that organizes the team's work into manageable sections; the Project Management Body of Knowledge defines the work-breakdown structure "A hierarchical decomposition of the total scope of work to be carried out by the project team to accomplish the project objectives and create the required deliverables." A work-breakdown structure element may be a product, service, or any combination thereof. A WBS provides the necessary framework for detailed cost estimating and control along with providing guidance for schedule development and control. WBS is a hierarchical and incremental decomposition of the project into phases and work packages, it is a tree structure. In a project or contract, the WBS is developed by starting with the end objective and successively subdividing it into manageable components in terms of size and responsibility which include all steps necessary to achieve the objective.
The work breakdown structure provides a common framework for the natural development of the overall planning and control of a contract and is the basis for dividing work into definable increments from which the statement of work can be developed and technical, schedule and labor hour reporting can be established. A work breakdown structure permits summing of subordinate costs for tasks, etc. into their successively higher level "parent" tasks, etc. For each element of the work breakdown structure, a description of the task to be performed is generated; this technique is used to organize the total scope of a project. The WBS is organized around the primary products of the project instead of the work needed to produce the products. Since the planned outcomes are the desired ends of the project, they form a stable set of categories in which the costs of the planned actions needed to achieve them can be collected. A well-designed WBS makes it easy to assign each project activity to one and only one terminal element of the WBS.
In addition to its function in cost accounting, the WBS helps map requirements from one level of system specification to another, for example, a cross reference matrix mapping functional requirements to high level or low level design documents. The WBS may be displayed horizontally in outline form, or vertically as a tree structure; the development of the WBS occurs at the start of a project and precedes detailed project and task planning. The concept of work breakdown structure developed with the Program Evaluation and Review Technique by the United States Department of Defense. PERT was introduced by the U. S. Navy in 1957 to support the development of its Polaris missile program. While the term "work breakdown structure" was not used, this first implementation of PERT did organize the tasks into product-oriented categories. By June 1962, DoD, NASA and the aerospace industry published a document for the PERT/COST system which described the WBS approach; this guide was endorsed by the Secretary of Defense for adoption by all services.
In 1968, the DoD issued "Work Breakdown Structures for Defense Materiel Items", a military standard requiring the use of work breakdown structures across the DoD. The document has been revised several times, most in 2018; the current version of this document can be found in "Work Breakdown Structures for Defense Material Items". It includes WBS definitions for specific defense materiel commodity systems, addresses WBS elements that are common to all systems. Defense Materiel Item categories from MIL-STD-881D are: Aircraft Systems Electronic/Generic Systems Missile/Ordnance Systems Strategic Missile Systems Sea Systems Space Systems Ground Vehicle Systems Unmanned Maritime Systems Launch Vehicle Systems Information Systems/Defense Business SystemsThe common elements identified in MIL-STD-881D, Appendix K are: Integration, assembly and checkout; the standard includes additional common elements unique to Space Systems, Launch Vehicle Systems, Strategic Missile Systems. In 1987, the Project Management Institute documented the expansion of these techniques across non-defense organizations.
The Project Management Body of Knowledge Guide provides an overview of the WBS concept, while the "Practice Standard for Work Breakdown Structures" is comparable to the DoD standard, but is intended for more general application. An important design principle for work breakdown structures is called the 100% rule, it has been defined as follows: The 100% rule states that the WBS includes 100% of the work defined by the project scope and captures all deliverables – internal, interim – in terms of the work to be completed, including project management. The 100% rule is one of the most important principles guiding the development and evaluation of the WBS; the rule applies at all levels within the hierarchy: the sum of the work at the "child" level must equal 100% of the work represented by the "parent" and the WBS should not include any work that falls outside the actual scope of the project, that is, it cann
Spreadsheet
A spreadsheet is an interactive computer application for organization and storage of data in tabular form. Spreadsheets developed as computerized analogs of paper accounting worksheets; the program operates on data entered in cells of a table. Each cell may contain either numeric or text data, or the results of formulas that automatically calculate and display a value based on the contents of other cells. A spreadsheet may refer to one such electronic document. Spreadsheet users can observe the effects on calculated values; this makes the spreadsheet useful for "what-if" analysis since many cases can be investigated without manual recalculation. Modern spreadsheet software can have multiple interacting sheets, can display data either as text and numerals, or in graphical form. Besides performing basic arithmetic and mathematical functions, modern spreadsheets provide built-in functions for common financial and statistical operations; such calculations as net present value or standard deviation can be applied to tabular data with a pre-programmed function in a formula.
Spreadsheet programs provide conditional expressions, functions to convert between text and numbers, functions that operate on strings of text. Spreadsheets have replaced paper-based systems throughout the business world. Although they were first developed for accounting or bookkeeping tasks, they now are used extensively in any context where tabular lists are built and shared. LANPAR, available in 1969, was the first electronic spreadsheet on mainframe and time sharing computers. LANPAR was an acronym: LANguage for Programming Arrays at Random. VisiCalc was the first electronic spreadsheet on a microcomputer, it helped turn the Apple II computer into a popular and used system. Lotus 1-2-3 was the leading spreadsheet. Excel now has the largest market share on the Macintosh platforms. A spreadsheet program is a standard feature of an office productivity suite. Web based spreadsheets are a new category. A spreadsheet consists of a table of cells arranged into rows and columns and referred to by the X and Y locations.
X locations, the columns, are represented by letters, "A", "B", "C", etc. while rows are represented by numbers, 1, 2, 3, etc. A single cell can be referred to by addressing its column, "C10" for instance; this electronic concept of cell references was first introduced in LANPAR and a variant used in VisiCalc, known as "A1 notation". Additionally, spreadsheets have the concept of a range, a group of cells contiguous. For instance, one can refer to the first ten cells in the first column with the range "A1:A10". LANPAR innovated forward referencing/natural order calculation which didn't re-appear until Lotus 123 and Microsoft's MultiPlan Version 2. In modern spreadsheet applications, several spreadsheets known as worksheets or sheets, are gathered together to form a workbook. A workbook is physically represented by a file, containing all the data for the book, the sheets and the cells with the sheets. Worksheets are represented by tabs that flip between pages, each one containing one of the sheets, although Numbers changes this model significantly.
Cells in a multi-sheet book add the sheet name to their reference, for instance, "Sheet 1! C10"; some systems extend this syntax to allow cell references to different workbooks. Users interact with sheets through the cells. A given cell can hold data by entering it in, or a formula, created by preceding the text with an equals sign. Data might include the string of text hello world, the number 5 or the date 16-Dec-91. A formula would begin with the equals sign, =5*3, but this would be invisible because the display shows the result of the calculation, 15 in this case, not the formula itself; this may lead to confusion in some cases. The key feature of spreadsheets is the ability for a formula to refer to the contents of other cells, which may in turn be the result of a formula. To make such a formula, one replaces a number with a cell reference. For instance, the formula =5*C10 would produce the result of multiplying the value in cell C10 by the number 5. If C10 holds the value 3 the result will be 15.
But C10 might hold its own formula referring to other cells, so on. The ability to chain formulas together is. Many problems can be broken down into a series of individual mathematical steps, these can be assigned to individual formulas in cells; some of these formulas can apply to ranges as well, like the SUM function that adds up all the numbers within a range. Spreadsheets share many principles and traits of databases, but spreadsheets and databases are not the same thing. A spreadsheet is just one table, whereas a database is a collection of many tables with machine-readable semantic relationships between them. While it is true that a workbook that contains three sheets is indeed a file containing multiple tables that can interact with each other, it lacks the relational structure of a database. Spreadsheets and databases are interoperable—sheets can be imported into databases to become tables within them, database queries can be exported into spreadsheets for further analysis. A spreadsheet program is one of the main components of an office productivity suite, which also contains a word processor, a presentation program, a database management system.
Programs within a suite use similar commands for similar functions. Sharing data between the components is easier tha
Tree structure
A tree structure or tree diagram is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree though the chart is upside down compared to an actual tree, with the "root" at the top and the "leaves" at the bottom. A tree structure is conceptual, appears in several forms. For a discussion of tree structures in specific fields, see Tree for computer science: insofar as it relates to graph theory, see tree, or tree. Other related pages are listed; the tree elements are called "nodes". The lines connecting elements are called "branches". Nodes without children are called leaf nodes, "end-nodes", or "leaves"; every finite tree structure has a member. This member is called root node; the root is the starting node. But the converse is not true: infinite tree structures may or may not have a root node; the names of relationships between nodes model the kinship terminology of family relations. The gender-neutral names "parent" and "child" have displaced the older "father" and "son" terminology, although the term "uncle" is still used for other nodes at the same level as the parent.
A node's "parent". "Sibling" nodes share the same parent node. A node's "uncles" are siblings of that node's parent. A node, connected to all lower-level nodes is called an "ancestor"; the connected lower-level nodes are "descendants" of the ancestor node. In the example, "encyclopedia" is the parent of its children. "Art" and "craft" are siblings, children of "culture", their parent and thus one of their ancestors. "encyclopedia", as the root of the tree, is the ancestor of "science", "culture", "art" and "craft". "science", "art" and "craft", as leaves, are ancestors of no other node. Tree structures can depict all kinds of taxonomic knowledge, such as family trees, the biological evolutionary tree, the evolutionary tree of a language family, the grammatical structure of a language, the way web pages are logically ordered in a web site, mathematical trees of integer sets, et cetera; the Oxford English Dictionary records use of both the terms "tree structure" and "tree-diagram" from 1965 in Noam Chomsky's Aspects of the Theory of Syntax.
In a tree structure there is one and only one path from any point to any other point. Computer science uses tree structures extensively For a formal definition see set theory, for a generalization in which children are not successors, see prefix order. Internet: usenet hierarchy Vacuum tubes Document Object Model's logical structure, Yahoo! Subject index, Curlie Operating system: directory structure Information management: Dewey Decimal System, PSH, this hierarchical bulleted list Management: hierarchical organizational structures Computer Science: binary search tree Red-Black Tree AVL tree R-tree Biology: evolutionary tree Business: pyramid selling scheme Project management: work breakdown structure Linguistics: Phrase structure trees Tree model of language change Sports: business chess, playoffs brackets Mathematics: Von Neumann universe Group theory: descendant trees There are many ways of visually representing tree structures. Always, these boil down to variations, or combinations, of a few basic styles: Classical node-link diagrams, that connect nodes together with line segments: Nested sets that use enclosure/containment to show parenthood, examples include TreeMaps and fractal maps: Layered "icicle" diagrams that use alignment/adjacency.
Lists or diagrams that use indentation, sometimes called "outlines" or "tree views". An outline: A tree view: A correspondence to nested parentheses was first noticed by Sir Arthur Cayley: Trees can be represented radially: Kinds of trees B-tree Dancing tree Decision tree Left-child right-sibling binary tree Tree Tree Tree Related articles Data drilling Hierarchical model: clustering and query Tree testing Identification of some of the basic styles of tree structures can be found in: Jacques Bertin, Semiology of Graphics, 1983, University of Wisconsin Press (2nd edition 1973, ISBN 978-0299090609. Manuel Lima, The Book of Trees: Visualizing Branches of Knowledge, Princeton Architectural Press, ISBN 978-1-616-89218-0 Visualization of phylogenetic trees on the T-REX server Using a tree structure to design a business process - from the Society for Technical Communication
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