Data Science: Learning (Definitions)

"Procedures for modifying the weights on the connection links in a neural net (also known as training algorithms, learning rules)." (Laurene V Fausett, "Fundamentals of Neural Networks: Architectures, Algorithms, and Applications", 1994)

"In the simplest form: self-adaptation at the processing element level. Weighted connections between processing elements or weights are adjusted to achieve specific results, eliminating the need for writing a specific algorithm for each problem. More generally: change of rules or behavior for a certain objective." (Guido J Deboeck and Teuvo Kohonen, "Visual explorations in finance with self-organizing maps", 2000)

"generic name for all behavioral changes that depend on experiences and improve the performance of a system. In a more restricted sense learning is identical with adaptation, especially selective modification of parameters of a system." (Teuvo Kohonen, "Self-Organizing Maps" 3rd Ed., 2001)

"A process whereby a training set of examples is used to generate a model that understands and generalizes the relationship between the descriptor variables and one or more response variables." (Glenn J Myatt, "Making Sense of Data: A Practical Guide to Exploratory Data Analysis and Data Mining", 2006)

"The process of automatically finding relations between inputs and outputs given examples of that relation." (Craig F Smith & H Peter Alesso, "Thinking on the Web: Berners-Lee, Gödel and Turing", 2008)

"An essential operation of acquiring, processing and storing information required by any intelligent system for evolution." (T R Gopalakrishnan Nair, "Cognitive Approaches for Intelligent Networks", 2015)

"Adaptation of synaptic weights of a neural network as training progresses, usually with the objective of minimizing a cost function." (Anand Parey & Amandeep S Ahuja, "Application of Artificial Intelligence to Gearbox Fault Diagnosis: A Review", 2016)

"Algorithm for changing the parameters of a function based on examples. Learning algorithms are said to be “supervised” when both inputs and desired outputs are given or “unsupervised” when only inputs are given. Reinforcement learning is a special case of a supervised learning algorithm when the only feedback is a reward for good performance." (Terrence J Sejnowski, "The Deep Learning Revolution", 2018)

"A phase in the machine learning methods that aggregates some information about the state actions for using in the future predictions of the events." (Derya Yiltas-Kaplan, "The Usage Analysis of Machine Learning Methods for Intrusion Detection in Software-Defined Networks", 2019)

Data Science: Hash Function (Definition)

"A function that maps a set of keys onto a set of addresses." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A function that maps a string of arbitrary length to a fixed size value in a deterministic manner. Such a function may or may not have cryptographic applications." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)

[cryptographic hash function:] "A function that takes an input string of arbitrary length and produces a fixed-size output for which it is unfeasible to find two inputs that map to the same output, and it is unfeasible to learn anything about the input from the output." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)

[one-way hash function:] "A hash function for which it is computationally unfeasible to determine anything about the input from the output." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)

"A function that operates on an arbitrary-length input value and returns a fixed-length hash value." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

[one-way hash:] "A one-way hash is an algorithm that transforms one string into another string (a fixed-length sequence of seemingly random characters) in such a way that the original string cannot be calculated by operations on the one-way hash value (i.e., the calculation is one way only). One-way hash values can be calculated for any string, including a person’s name, a document, or an image. For any input string, the resultant one-way hash will always be the same. If a single byte of the input string is modified, the resulting one-way hash will be changed and will have a totally different sequence than the one-way hash sequence calculated for the unmodified string. One-way hash values can be made sufficiently long (e.g., 256 bits) that a hash string collision (i.e., the occurrence of two different input strings with the same one-way hash output value) is negligible." (Jules H Berman, "Principles of Big Data: Preparing, Sharing, and Analyzing Complex Information", 2013)

"A hash function is an algorithm that maps from an input, for example, a string of characters, to an output string. The size of the input can vary, but the size of the output is always the same." (Dan Sullivan, "NoSQL for Mere Mortals®", 2015)

[one-way hash:] "Cryptographic process that takes an arbitrary amount of data and generates a fixed-length value. Used for integrity protection." (Adam Gordon, "Official (ISC)2 Guide to the CISSP CBK" 4th Ed., 2015)

"A function that takes as input the key of an element and produces an integer as output" (Nell Dale et al, "Object-Oriented Data Structures Using Java" 4th Ed., 2016)

"encryption methods that use no keys." (Manish Agrawal, "Information Security and IT Risk Management", 2014)

"A function that operates on an arbitrary-length input value and returns a fixed-length hash value." (Oracle, "Oracle Database Concepts")

Data Science: Hash (Definitions)

"A number (often a 32-bit integer) that is derived from column values using a lossy compression algorithm. DBMSs occasionally use hashing to speed up access, but indexes are a more common mechanism." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A set of characters generated by running text data through certain algorithms. Often used to create digital signatures and compare changes in content." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"Hash, a mathematical method for creating a numeric signature based on content; these days, often unique and based on public key encryption technology." (Bo Leuf, "The Semantic Web: Crafting infrastructure for agency", 2006)

[hash code:] "An integer calculated from an object. Identical objects have the same hash code. Generated by a hash method." (Michael Fitzgerald, "Learning Ruby", 2007)

"An unordered collection of data where keys and values are mapped. Compare with array." (Michael Fitzgerald, "Learning Ruby", 2007)

"A cryptographic hash is a fixed-size bit string that is generated by applying a hash function to a block of data. Secure cryptographic hash functions are collision-free, meaning there is a very small possibility of generating the same hash for two different blocks of data. A secure cryptographic hash function should also be one-way, meaning it is infeasible to retrieve the original text from the hash." (Michael Coles & Rodney Landrum, "Expert SQL Server 2008 Encryption", 2008)

"A hash is the result of applying a mathematical function or transformation on data to generate a smaller 'fingerprint' of the data. Generally, the most useful hash functions are one-way collision-free hashes that guarantee a high level of uniqueness in their results." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"The output of a hash function." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)

"A number based on the hash value of a string." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"1.Data allocated in an algorithmically randomized fashion in an attempt to evenly distribute data and smooth access patterns. 2.Verb. To calculate a hash key for data." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A hash is the result of applying a mathematical function or transformation on data to generate a smaller 'fingerprint' of the data. Generally, the most useful hash functions are one-way collision-free hashes that guarantee a high level of uniqueness in their results." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide" 3rd Ed., 2012)

"An unordered association of key/value pairs, stored such that you can easily use a string key to look up its associated data value. This glossary is like a hash, where the word to be defined is the key and the definition is the value. A hash is also sometimes septisyllabically called an “associative array”, which is a pretty good reason for simply calling it a 'hash' instead." (Jon Orwant et al, "Programming Perl" 4th Ed., 2012)

"In a hash cluster, a unique numeric ID that identifies a bucket. Oracle Database uses a hash function that accepts an infinite number of hash key values as input and sorts them into a finite number of buckets. Each hash value maps to the database block address for the block that stores the rows corresponding to the hash key value (department 10, 20, 30, and so on)." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The result of applying a mathematical function or transformation to data to generate a smaller 'fingerprint' of the data. Generally, the most useful hash functions are one-way, collision-free hashes that guarantee a high level of uniqueness in their results." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide" 4th Ed., 2015)

[hash code:] "The output of the hash function that is associated with the input object" (Nell Dale et al, "Object-Oriented Data Structures Using Java" 4th Ed., 2016)

"A numerical value produced by a mathematical function, which generates a fixed-length value typically much smaller than the input to the function. The function is many to one, but generally, for all practical purposes, each file or other data block input to a hash function yields a unique hash value." (William Stallings, "Effective Cybersecurity: A Guide to Using Best Practices and Standards", 2018)

"The number generated by a hash function to indicate the position of a given item in a hash table." (IEEE 610.5-1990)

Strategic Management: Objectives (Just the Quotes)

"The published objectives of a company will never reflect all the goals and values of the corporation as an institution or its management as human beings."(Richard Eells, California Management Review, 1959)

"Man will exercise self-direction and self-control in the service of objectives to which he is committed." (Douglas McGregor, "The Human Side of Enterprise", 1960)

"The decision which achieves organization objectives must be both (1) technologically sound and (2) carried out by people. If we lose sight of the second requirement or if we assume naively that people can be made to carry out whatever decisions are technically sound - we run the risk of decreasing rather than increasing the effectiveness of the organization." (Douglas McGregor, "The Human Side of Enterprise", 1960)

"The essential task of management is to arrange organizational conditions and methods of operations so that people can achieve their own goals best by directing their own efforts toward organizational objectives." (Douglas McGregor, "The Human Side of Enterprise", 1960)

"It is an axiom of program budgeting that the budget should facilitate the process of alternative methods of obtaining objectives." (Chester Wright, "Program Budgeting and Cost Benefit Analysis", 1969)

"[One] must not always assume that obscure and obfuscated objectives are totally lacking in function.(Harley H Hinrichs, "Program Budgeting and Cost Benefit Analysis", 1969)

"[Management by objectives is] a process whereby the superior and the subordinate managers of an enterprise jointly identify its common goals, define each individual's major areas of responsibility in terms of the results expected of him, and use these measures as guides for operating the unit and assessing the contribution of each of its members." (Robert House, "Administrative Science Quarterly", 1971)

"A manager [...] sets objectives [...] organizes [...] motivates and communicates [...] measure[s] [...] develops people. Every manager does these thingsknowingly or not. A manager may do them well, or may do them wretchedly, but always does them." (Peter F Drucker, "People and Performance", 1977)

"Objectives are not fate; they are direction. They are not commands; they are commitments. They do not determine the future; they are means to mobilize the resources and energies of the business for the making of the future." (Peter F Drucker, "People and Performance", 1977)

"[...] when a variety of tasks have all to be performed in cooperation, synchronization, and communication, a business needs managers and a management. Otherwise, things go out of control; plans fail to turn into action; or, worse, different parts of the plans get going at different speeds, different times, and with different objectives and goals, and the favor of the 'boss' becomes more important than performance." (Peter F Drucker, "People and Performance", 1977)

"Any approach to strategy quickly encounters a conflict between corporate objectives and corporate capabilities. Attempting the impossible is not good strategy; it is just a waste of resources." (Bruce Henderson, Henderson on Corporate Strategy, 1979)

"There are always 'class or prestige' gaps between various levels of management. There are also functional gaps between working units of the organization. If we superimpose the management gaps on top of the functional gaps, we find that companies are made up of small operational islands that refuse to communicate with one another for fear that giving up information may strengthen their opponents. The project manager’s responsibility is to get these islands to communicate cross-functionally toward common goals and objectives." (Harold Kerzner, "Project Management: A systems approach to planning, scheduling, and controlling", 1979)

"Given a multilevel organization having component groups which perform a variety of functions in order to accomplish a unified objective, an MIS [Management Information System] is an integrated structure of data bases and information flow over all levels and components, whereby information collection and transfer is optimized to meet the needs of the organization." (Larry E Long, "Manager's Guide to Computers and Information Systems", 1983)

"Management by objectives is a philosophy of managing that is based on identifying purposes, objectives, and desired results, establishing a realistic program for obtaining these results, and evaluating performance in achieving them." (R Henry Miglione, "An MBO Approach to Long-Range Planning", 1983)

"Public accounting taught me analytical approaches to business problems, objective reasoning, and the highest order of discipline in making factual presentations." (Harold Geneen, "Managing", 1984)

"Management has a responsibility to explain to the employee how the routine job contributes to the business's objectives. If management cannot explain the value of the job, then it should be eliminated and the employee reassigned." (Douglas M Reid, Harvard Business Review, 1986)

"Organizations are complex and paradoxical phenomena that can be understood in many different ways. Many of our taken-for-granted ideas about organizations are metaphorical, even though we may not recognize them as such. For example, we frequently talk about organizations as if they were machines designed to achieve predetermined goals and objectives, and which should operate smoothly and efficiently. And as a result of this kind of thinking, we often attempt to organize and manage them in a mechanistic way, forcing their human qualities into a background role. By using different metaphors to understand the complex and paradoxical character of organizational life, we are able to manage and design organizations in ways that we may not have thought possible before." (Gareth Morgan, "Images of Organization", 1986)

"[...] strategic planning and crisis management are complimentary. They coexist comfortably because both deal with the management of change. Crisis management concentrates on those brief moments of instability that must be dealt with first in order to get on with the larger and less time-sensitive job of reaching strategic objectives." (Gerald C Meyers, "When It Hits the Fan", 1986)

"The 'management by objectives' school [...] suggests that detailed objectives be spelled out at all levels in the corporation. This method is feasible at lower levels of management, but it becomes unworkable at the upper levels. The top manager must think out objectives in detail, but ordinarily some of the objectives must be withheld, or at least communicated to the organization in modest doses. A conditioning process that may stretch over months or years is necessary in order to prepare the organization for radical departures from what it is currently striving to attain." (H Edward Wrapp, Harvard Business Review on Human Relations, 1986)

"Top managers are currently inundated with reams of information concerning the organizational units under their supervision. Behind this information explosion lies a seemingly logical assumption made by information specialists and frequently accepted by line managers: if top management can be supplied with more 'objective' and 'accurate' quantified information, they will make 'better' judgments about the performance of their operating units. [...] A research study we have recently completed indicates that quantified performance information may have a more limited role than is currently assumed or envisioned; in fact, managers rely more on subjective information than they do on so called 'objective' statistics in assessing the overall performance of lower-level units." (Larry E. Greiner et al, Harvard Business Review on Human Relations, 1986)

"The most important reason for our success is we set our objectives and make sure we follow through on them." (Annette B Roux, The New York Times, 1987)

"[management by objectives] has become one more way to make organizations behave like machines." (Julien Phillips, "Success", 1988)

"The major fault in this process - and thus, in the way we were making decisions - is that it lacks an organizing framework. In pursuing a variety of goals and objectives, in whatever situation we manage, we often fail to see that some of them are in conflict and that the achievement of one might come at the expense of achieving another. In weighing up the actions we might take to reach our goals and objectives, we have no way to account for nature's complexity and only rarely factor it in." (Allan Savory & Jody Butterfield, "Holistic Management: A new framework for decision making", 1988)

"A process perspective sees not individual tasks in isolation, but the entire collection of tasks that contribute to a desired outcome. Narrow points of view are useless in a process context. It just won't do for each person to be concerned exclusively with his or her own limited responsibility, no matter how well these responsibilities are met. When that occurs, the inevitable result is working at cross–purpose, misunderstanding, and the optimization of the part at the expense of the whole. Process work requires that everyone involved be directed toward a common goal; otherwise, conflicting objectives and parochial agendas impair the effort."  (James A Champy & Michael M Hammer, "Reengineering the Corporation", 1993)

"A leader’s most important job is creating and constantly adjusting this strategic bridge between goals and objectives." (Richard Rumelt, "Good Strategy Bad Strategy", 2011)

"An OBJECTIVE […] is simply WHAT is to be achieved, no more and no less. By definition, objectives are significant, concrete, action oriented, and (ideally) inspirational. When properly designed and deployed, they’re a vaccine against fuzzy thinking - and fuzzy execution." (John Doerr, "Measure what Matters", 2018)

Strategic Management: Business Impact Analysis (Definitions)

"The process of delineating the functions most critical to the survival of a business." (Yvette Ghormley, "Business Continuity and Disaster Recovery Plans", 2009)

"A management-level analysis which identifies the impacts of losing company resources. The BIA measures the effect of resource loss and escalating losses over time, in order to provide senior management with reliable data on which to base decisions concerning risk mitigation and continuity planning." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)

"A method or exercise to determine the impact of losing the support or availability of a resource." (Linda Volonino & Efraim Turban, "Information Technology for Management" 8th Ed., 2011)

"Aims to (a) identify critical business processes, stakeholders, assets, resources and internal/external dependencies and (b) assesses and evaluates potential damages or losses at business level that may be caused by a threat to IT landscape." (Ulrich Winkler & Wasif Gilani, "Business Continuity Management of Business Driven IT Landscapes", 2012)

"A process used to analyze the business and identify critical functions and services. The BIA also helps the organization determine the cost impact of losing these functions and services. Organizations use the results as part of an overall business continuity plan." (Darril Gibson, "Effective Help Desk Specialist Skills", 2014)

"The identification of services and products that are critical to the organization." (Manish Agrawal, "Information Security and IT Risk Management", 2014)

"The process of analysing activities and the effect that a business disruption might have upon them." (David Sutton, "Information Risk Management: A practitioner’s guide", 2014)

"An exercise that determines the impact of losing the support of any resource to an organization, establishes the escalation of that loss over time, identifies the minimum resources needed to recover, and prioritizes the recovery of processes and supporting systems." (Adam Gordon, "Official (ISC)2 Guide to the CISSP CBK" 4th Ed., 2015)

"A functional analysis in which a team collects data, documents business functions, develops a hierarchy of business functions, and applies a classification scheme to indicate each individual function’s criticality level." (Shon Harris & Fernando Maymi, "CISSP All-in-One Exam Guide" 8th Ed., 2018)

"The analysis of an information system’s requirements, functions, and interdependencies used to characterize system contingency requirements and priorities in the event of a significant disruption." (William Stallings, "Effective Cybersecurity: A Guide to Using Best Practices and Standards", 2018)

"A business continuity management activity which is mainly intended for defining the core business functions, the recovery priorities regarding these functions and the corresponding time required for the resumption of each function." (Athanasios Podaras et al, "Regression-Based Recovery Time Predictions in Business Continuity Management: A Public College Case Study", 2021)

"Activity that identifies the VMF and their dependencies" (ITIL)

"An analysis of an information system’s requirements, functions, and interdependencies used to characterize system contingency requirements and priorities in the event of a significant disruption." (CNSSI 4009-2015)

Systems Engineering: Synergy (Just the Quotes)

"The constructive process inheres in all forms of synergy, and the cooperation of antithetical forces in nature always results in making, that is, in creating something that did not exist before. But in the organic world this character of structure becomes the leading feature, and we have synthetic products consisting of tissues and organs serving definite purposes, which we call functions." (Lester F Ward, "Pure Sociology", 1903)

"[...] there is a universal principle, operating in every department of nature and at every stage of evolution, which is conservative, creative and constructive. [...] I have at last fixed upon the word synergy, as the term best adapted to express its twofold character of ‘energy’ and ‘mutuality’ or the systematic and organic ‘working together’ of the antithetical forces of nature. [...] Synergy is a synthesis of work, or synthetic work, and this is what is everywhere taking place. It may be said to begin with the primary atomic collision in which mass, motion, time, and space are involved, and to find its simplest expression in the formula for force, which implies a plurality of elements, and signifies an interaction of these elements." (Lester F Ward, "Pure Sociology", 1903)

"Social structures are the products of social synergy, i.e., of the interaction of different social forces, all of which, in and of themselves, are destructive, but whose combined effect, mutually checking, constraining, and equilibrating one another, is to produce structures. The entire drift is toward economy, conservatism, and the prevention of waste. Social structures are mechanisms for the production of results, and the results cannot be secured without them. They are reservoirs of power." (James Q Dealey & Lester F Ward, "A Text-book of Sociology", 1905)

"The true nature of the universal principle of synergy pervading all nature and creating all the different kinds of structure that we observe to exist, must now be made clearer. Primarily and essentially it is a process of equilibration, i.e., the several forces are first brought into a state of partial equilibrium. It begins in collision, conflict, antagonism, and opposition, and then we have the milder phases of antithesis, competition, and interaction, passing next into a modus vivendi, or compromise, and ending in collaboration and cooperation. […] The entire drift is toward economy, conservatism, and the prevention of waste." (James Q Dealey & Lester F Ward, "A Text-book of Sociology", 1905)

"Synergy is the only word in our language that means behavior of whole systems unpredicted by the separately observed behaviors of any of the system's separate parts or any subassembly of the system's parts." (R Buckminster Fuller, "Operating Manual for Spaceship Earth", 1963)

"Synergy means behavior of whole systems unpredicted by the behavior of their parts taken separately." (R Buckminster Fuller, "Synergetics: Explorations in the Geometry of Thinking", 1975)

"[...] synergy is the consequence of the energy expended in creating order. It is locked up in the viable system created, be it an organism or a social system. It is at the level of the system. It is not discernible at the level of the system. It is not discernible at the level of the system’s components. Whenever the system is dismembered to examine its components, this binding energy dissipates." (J-C Spender, "Organizational Knowledge, Collective Practice and Penrose Rents", 1999)

"There is a multilayering of global networks in the key strategic activities that structure and destructure the planet. When these multilayered networks overlap in some node, when there is a node that belongs to different networks, two major consequences follow. First, economies of synergy between these different networks take place in that node: between financial markets and media businesses; or between academic research and technology development and innovation; between politics and media." (Manuel Castells, "The Rise of the Network Society", 1996)

"With the growing interest in complex adaptive systems, artificial life, swarms and simulated societies, the concept of 'collective intelligence' is coming more and more to the fore. The basic idea is that a group of individuals (e. g. people, insects, robots, or software agents) can be smart in a way that none of its members is. Complex, apparently intelligent behavior may emerge from the synergy created by simple interactions between individuals that follow simple rules." (Francis Heylighen, "Collective Intelligence and its Implementation on the Web", 1999)

"Systems thinking means the ability to see the synergy of the whole rather than just the separate elements of a system and to learn to reinforce or change whole system patterns. Many people have been trained to solve problems by breaking a complex system, such as an organization, into discrete parts and working to make each part perform as well as possible. However, the success of each piece does not add up to the success of the whole. to the success of the whole. In fact, sometimes changing one part to make it better actually makes the whole system function less effectively." (Richard L Daft, "The Leadership Experience", 2002)

"Self-organization can be seen as a spontaneous coordination of the interactions between the components of the system, so as to maximize their synergy. This requires the propagation and processing of information, as different components perceive different aspects of the situation, while their shared goal requires this information to be integrated. The resulting process is characterized by distributed cognition: different components participate in different ways to the overall gathering and processing of information, thus collectively solving the problems posed by any perceived deviation between the present situation and the desired situation." (Carlos Gershenson & Francis Heylighen, "How can we think the complex?", 2004)

"Synergy happens when people, things, or events combine to produce a larger impact than they would if each acted separately." (Thomas Homer-Dixon, "The Upside of Down: Catastrophe, Creativity, and the Renewal of Civilization", 2006)

[synergy:] "Measure describing how one agent or system increases the satisfaction of other agents or systems." (Carlos Gershenson, "Design and Control of Self-organizing Systems", 2007)

"To develop a Control, the designer should find aspect systems, subsystems, or constraints that will prevent the negative interferences between elements (friction) and promote positive interferences (synergy). In other words, the designer should search for ways of minimizing frictions that will result in maximization of the global satisfaction" (Carlos Gershenson, "Design and Control of Self-organizing Systems", 2007)

"Synergy is the combined action that occurs when people work together to create new alternatives and solutions. In addition, the greatest opportunity for synergy occurs when people have different viewpoints, because the differences present new opportunities. The essence of synergy is to value and respect differences and take advantage of them to build on strengths and compensate for weaknesses." (Richard L Daft, "The Leadership Experience" 4th Ed., 2008)

"Synergy occurs when organizational parts interact to produce a joint effect that is greater than the sum of the parts acting alone. As a result the organization may attain a special advantage with respect to cost, market power, technology, or employee." (Richard L Daft, "The Leadership Experience" 4th Ed., 2008)

"In short, synergy is the consequence of the energy expended in creating order. It is locked up in the viable system created, be it an organism or a social system. It is at the level of the system. It is not discernible at the level of the system. It is not discernible at the level of the system's components. Whenever the system is dismembered to examine its components, this binding energy dissipates." (J-C Spender, "Organizational Knowledge, Collective Practice and Penrose Rents", 2009)

"Synergy is defined as the surplus gained by working together. A task which couldn’t be fulfilled by one individual, can be completed by the work of different individuals together. To maximize synergy, first, the initial task is divided into different sub-tasks. Different agents perform different tasks, which is called division of labor. An end product of one work is used for another work, which is called workflow. Finally, everything needs to be put together. We call this aggregation. This isn’t as linear as it looks. At every step in the process it can happen that a task is divided into sub tasks or aggregated with other tasks." (Evo Busseniers, "Self-organization versus hierarchical organization", [thesis] 2018)

DBMS: Scalar Aggregate (Definitions)

"An aggregate function that produces a single value from a select statement that does not include a group by clause. This is true whether the aggregate function is operating on all the rows in a table or on a subset of rows defined by a where clause." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

[vector aggregate:] "A value that results from using an aggregate function with a group by clause." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"When aggregate functions are applied to the whole or partial table without the GROUP BY clause and return only one row." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

[vector aggregates:] "When aggregate functions are used with the GROUP BY clause, they return values for each group. These are called vector aggregates." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A function applied to all of the rows in a table (producing a single value per function). An aggregate function in the select list with no GROUP BY clause applies to the whole table and is an example of a scalar." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

[vector aggregate:] "Functions applied to all rows that have the same value in a specified column or expression by using the GROUP BY clause and, optionally, the HAVING clause (producing a value for each group per function)." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An aggregate value that is calculated on the data source. Depending on the data source, server aggregates can be treated as detail data or as aggregates based on the dataset option InterpretSubtotalsAsDetails." (Microsoft Technet)

[aggregate of aggregates:] "A summary value calculated from aggregates, such as the maximum of a set of sums." (Microsoft Technet)

 "An aggregate function, such as MIN(), MAX(), or AVG(), that is specified in a SELECT statement column list that contains only aggregate functions." (Microsoft Technet)

DBMS: Hash Table (Definitions)

"A data structure used internally by Perl for implementing associative arrays (hashes) efficiently. See also bucket." (Jon Orwant et al, "Programming Perl" 4th Ed., 2012)

[hash cluster:] "A type of table cluster that is similar to an indexed cluster, except the index key is replaced with a hash function. No separate cluster index exists. In a hash cluster, the data is the index." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"An in-memory data structure that associates join keys with rows in a hash join. For example, in a join of the employees and departments tables, the join key might be the department ID. A hash function uses the join key to generate a hash value. This hash value is an index in an array, which is the hash table." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The data structure used to store elements using hashing" (Nell Dale et al, "Object-Oriented Data Structures Using Java" 4th Ed., 2016)

"An object that is like a dictionary or an associative array. A hash table stores and retrieves elements using key values called hashcodes. See also hashcode." (Daniel Leuck et al, "Learning Java" 5th Ed., 2020)

[sorted hash cluster:] "A hash cluster that stores the rows corresponding to each value of the hash function in such a way that the database can efficiently return them in sorted order. The database performs the optimized sort internally." (Oracle, "Oracle Database Concepts")

"An in-memory data structure that associates join keys with rows in a hash join. For example, in a join of the employees and departments tables, the join key might be the department ID. A hash function uses the join key to generate a hash value. This hash value is an index in an array, which is the hash table." (Oracle, "Oracle Database Concepts")

"A two-dimensional table of items in which a hash function is applied to the key of each item to determine its hash value. The hash value identifies each item's primary position in the table, and if this position is already occupied, the item is inserted either in an overflow table or in another available position in the table." (IEEE 610.5-1990)

DBMS: Nondeterministic Function (Definitions)

"A function that may generate different outputs each time it is run, even if the inputs are always the same." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A function is non-deterministic if it can return different results when provided with the same input. The RAND function is non-deterministic because it returns a different randomly generated number each time it is called." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A characteristic of a function that means the function can return different results when provided with the same input. For example, the RAND function is nondeterministic because it returns a different randomly generated number each time it is called." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"Nondeterministic functions return different values when they’re invoked with the same arguments." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Typically refers to functions such as nondeterministic functions. A nondeterministic function returns different results when called with the same input values. As an example, GETDATE() would return different results at different times. Indexed views can not include nondeterministic functions." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"An application whose state of execution cannot be predicted is said to be nondeterministic. Since the operating system schedules threads for execution on processor resources and there are too many factors that influence the OS scheduling, the state of execution of a concurrent application cannot be reliably predicted. Typically, incorrect use of nondeterminism in concurrent applications will be evidenced by the application returning different results from the same inputs." (Clay Breshears, "The Art of Concurrency", 2009)

"Exhibiting a lack of deterministic behavior, so results can vary from run to run of an algorithm. See more in the definition for deterministic." (Michael McCool et al, "Structured Parallel Programming", 2012)

"A user-defined function whose result is not solely dependent on the values of the input arguments. That is, successive invocation with the same argument value can produce a different answer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Deterministic Function (Definitions)

"A function that always generates the same outputs, given the same inputs." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A function is deterministic if it always returns the same output when presented with the same input." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A characteristic of a function that means the function always returns the same output when presented with the same input." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"Deterministic functions return the same value each time they’re invoked with the same arguments." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Whether a function always returns the same output given the same inputs." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A deterministic function is one which, given a specific set of inputs, will always produce the same result. The SQL Server decryption functions are an example of deterministic functions. SQL Server’s symmetric encryption functions, however, generate a random IV so the result is nondeterministic." (Michael Coles & Rodney Landrum, , "Expert SQL Server 2008 Encryption", 2008)

"Typically refers to functions such as deterministic functions. A deterministic function always returns the same result when called with the same input values. Indexed VIEWs require any functions used within the indexed VIEW to be deterministic. As a comparison, see nondeterministic." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"a computation situation in which the execution time of an action sequence is known precisely." (Bruce P Douglass, "Real-Time Agility: The Harmony/ESW Method for Real-Time and Embedded Systems Development", 2009)

"Given the same inputs, a deterministic application will present the same (observable) results each and every time." (Clay Breshears, "The Art of Concurrency", 2009)

"A deterministic algorithm is an algorithm that behaves predictably. Given a particular input, a deterministic algorithm will always produce the same output. The definition of what is the “same” may be important due to limited precision in mathematical operations and the likelihood that optimizations including parallelization will rearrange the order of operations. These are often referred to as “rounding” differences, which result when the order of mathematical operations to compute answers differs between the original program and the final concurrent program. Concurrency is not the only factor that can lead to non-deterministic algorithms but in practice it is often the cause. Use of programming models with sequential semantics and eliminating data races with proper access controls will generally eliminate non-determinism other than the 'rounding' differences." (Michael McCool et al, "Structured Parallel Programming", 2012)

"Having a predictable value with a very narrow range of variance. As a result, deterministic values do not require the use of probability distributions to describe their behavior in business analysis methods or decisions and can usually be represented by a constant value." (Kenneth A Shaw, "Integrated Management of Processes and Information", 2013)

"A user-defined function with a result that is dependent on the values of the input arguments. Successive invocations with the same input values produce the same answer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Function (Definitions)

"A set of instructions that operates as a single logical unit, can be called by name, accepts input parameters, and returns information. In programming languages such as C, a function is a named subroutine of a program that encapsulates some logic. The function can be called by name, using parameters to pass data into the function and retrieve data produced by the function. In Transact-SQL, a function is a unit of syntax consisting of a keyword and, usually, a set of parameters. There are several categories of Transact-SQL functions: string, math, system, niladic, text and image, date, aggregate, and conversion functions." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A program that returns a value to the program or environment from which it is called." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A section of code that operates as a single logical unit. Transact-SQL supports both built-in functions and user-defined functions. The built-in functions cannot be modified by SQL Server 2000 users, whereas users can create and modify user- defined functions." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A named set of predefined programming language commands that performs a specific task given zero, one, or more arguments and returns a value." (Bob Bryla, "Oracle Database Foundations", 2004)

"A programming unit or expression returning a single value, also allowing determinant values to be passed in as parameters. Thus, parameter values can change the outcome or return result of a function. The beauty of a function is that it is self-contained and can thus be embedded into an expression." (Gavin Powell, "Beginning Database Design", 2006)

"A set of instructions that operates as a single logical unit." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A centralized, server-based routine that can be included as part of your Transact-SQL statements. Typically used to streamline logic and reduce the amount of required programming effort, you can build your own functions." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"Functions are routines that can accept parameters, perform an action, and return the result of that action. SQL Server includes many built-in functions. User- defined functions can be created to meet specific needs." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A piece of code that operates as a single logical unit. A function is called by name, accepts optional input parameters, and returns a status and optional output parameters. Many programming languages support functions, including C, Visual Basic, and Transact-SQL. Transact-SQL supplies built-in functions, which cannot be modified, and supports user-defined functions, which can be created and modified by users." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A small program that performs one task and returns a single value. It may be built into the SQL language or written by a user, database administrator, or application programmer." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A piece of code that operates as a single logical unit. A function is called by name, accepts optional input parameters, and returns a status and optional output parameters. Many programming languages support functions." (SQL Server 2012 Glossary, "Microsoft", 2012)

"A predefined algorithm supported by the DBMS for converting, manipulating, or calculating data based upon input. Functions can be used within SQL statements any place an expression can be used." (Craig S Mullins, "Database Administration", 2012)

"A relationship between a set of input data values and a set of result values that is used to extend and customize SQL or XQuery. Functions are invoked from elements of SQL statements such as the select list or the FROM clause and from XQuery as primary expressions." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

OOP: Function (Definitions)

"(1) A defined objective or characteristic action of a system or component. For example, a system may have inventory control as its primary function. (2) A software module that performs a specific action, is invoked by the appearance of its name in an expression, may receive input values, and returns a single value." (IEEE," IEEE Standard Glossary of Software Engineering Terminology", 1990) 

"A set of instructions that operates as a single logical unit, can be called by name, accepts input parameters, and returns information. In programming languages such as C, a function is a named subroutine of a program that encapsulates some logic. The function can be called by name, using parameters to pass data into the function and retrieve data produced by the function." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A block of code that performs a service, such as adding two numbers or printing to the screen." (Jesse Liberty, "Sams Teach Yourself C++ in 24 Hours" 3rd Ed., 2001)

"A program that returns a value to the program or environment from which it is called." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A routine that processes data inside a program." (Greg Perry, "Sams Teach Yourself Beginning Programming in 24 Hours" 2nd Ed., 2001)

"A block of statements identified by a name that can accept one or more arguments passed to it by value and can optionally return a value. Functions can be local (static) to the file in which they're defined or global, in which case they can be called from functions or methods defined in other files." (Stephen G Kochan, "Programming in Objective-C", 2003)

"A named set of predefined programming language commands that performs a specific task given zero, one, or more arguments and returns a value." (Bob Bryla, "Oracle Database Foundations", 2004)

"A piece of code that operates as a single logical unit. A function is called by name, accepts optional input parameters, and returns a status and optional output parameters. Many programming languages support functions, including C, Visual Basic, and Transact-SQL. Transact-SQL supplies built-in functions, which cannot be modified, and supports user-defined functions, which can be created and modified by users." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A block of statements identified by a name that can accept one or more arguments passed to it by value and can optionally return a value. Functions can be either local (static) to the file in which they’re defined or global, in which case they can be called from functions or methods defined in other files." (Stephen G Kochan, "Programming in Objective-C" 4th Ed., 2011)

"A packaged set of code that other pieces of code can invoke and that returns a result value." (Rod Stephens, "Stephens' Visual Basic Programming 24-Hour Trainer", 2011)

"A single block of code that accomplishes a single task and can be reused." (Matt Telles, "Beginning Programming", 2014)