Association rule learningAssociation rule learning is a rule-based machine learning method for discovering interesting relations between variables in large databases. It is intended to identify strong rules discovered in databases using some measures of interestingness. In any given transaction with a variety of items, association rules are meant to discover the rules that determine how or why certain items are connected.
Nullable typeNullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type. In statically typed languages, a nullable type is an option type, while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null value. NULL is frequently used to represent a missing value or invalid value, such as from a function that failed to return or a missing field in a database, as in NULL in SQL.
Turing degreeIn computer science and mathematical logic the Turing degree (named after Alan Turing) or degree of unsolvability of a set of natural numbers measures the level of algorithmic unsolvability of the set. The concept of Turing degree is fundamental in computability theory, where sets of natural numbers are often regarded as decision problems. The Turing degree of a set is a measure of how difficult it is to solve the decision problem associated with the set, that is, to determine whether an arbitrary number is in the given set.
Property rights (economics)Property rights are constructs in economics for determining how a resource or economic good is used and owned, which have developed over ancient and modern history, from Abrahamic law to Article 17 of the Universal Declaration of Human Rights. Resources can be owned by (and hence be the property of) individuals, associations, collectives, or governments. Property rights can be viewed as an attribute of an economic good.
Product differentiationIn economics and marketing, product differentiation (or simply differentiation) is the process of distinguishing a product or service from others to make it more attractive to a particular target market. This involves differentiating it from competitors' products as well as from a firm's other products. The concept was proposed by Edward Chamberlin in his 1933 book, The Theory of Monopolistic Competition. Firms have different resource endowments that enable them to construct specific competitive advantages over competitors.
Fixed investmentFixed investment in economics is the purchasing of newly produced fixed capital. It is measured as a flow variable – that is, as an amount per unit of time. Thus, fixed investment is the accumulation of physical assets such as machinery, land, buildings, installations, vehicles, or technology. Normally, a company balance sheet will state both the amount of expenditure on fixed assets during the quarter or year, and the total value of the stock of fixed assets owned.
Black swan theoryThe black swan theory or theory of black swan events is a metaphor that describes an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight. The term is based on an ancient saying that presumed black swans did not exist - a saying that became reinterpreted to teach a different lesson after they were discovered in Australia.
