Price ceilingA price ceiling is a government- or group-imposed price control, or limit, on how high a price is charged for a product, commodity, or service. Governments use price ceilings to protect consumers from conditions that could make commodities prohibitively expensive. Such conditions can occur during periods of high inflation, in the event of an investment bubble, or in the event of monopoly ownership of a product, all of which can cause problems if imposed for a long period without controlled rationing, leading to shortages.
Discrimination par les prixvignette|Illustration de la discrimination par les prix des articles La discrimination par les prix désigne la modulation par agent des prix de son offre en fonction des caractéristiques connues ou supposées de la demande. Classiquement, on distingue trois types de discriminations par les prix en fonction de l'information dont dispose l'agent discriminateur : Discrimination de premier type, ou discrimination parfaite : le prix est fixé en fonction de la qualité de l'acheteur.
Universal setIn set theory, a universal set is a set which contains all objects, including itself. In set theory as usually formulated, it can be proven in multiple ways that a universal set does not exist. However, some non-standard variants of set theory include a universal set. Many set theories do not allow for the existence of a universal set. There are several different arguments for its non-existence, based on different choices of axioms for set theory. In Zermelo–Fraenkel set theory, the axiom of regularity and axiom of pairing prevent any set from containing itself.
Ensemble flouLa théorie des sous-ensembles flous est une théorie mathématique du domaine de l’algèbre abstraite. Elle a été développée par Lotfi Zadeh en 1965 afin de représenter mathématiquement l'imprécision relative à certaines classes d'objets et sert de fondement à la logique floue. Les sous-ensembles flous (ou parties floues) ont été introduits afin de modéliser la représentation humaine des connaissances, et ainsi améliorer les performances des systèmes de décision qui utilisent cette modélisation.
Set-builder notationIn set theory and its applications to logic, mathematics, and computer science, set-builder notation is a mathematical notation for describing a set by enumerating its elements, or stating the properties that its members must satisfy. Defining sets by properties is also known as set comprehension, set abstraction or as defining a set's intension. Set (mathematics)#Roster notation A set can be described directly by enumerating all of its elements between curly brackets, as in the following two examples: is the set containing the four numbers 3, 7, 15, and 31, and nothing else.
Price fixingPrice fixing is an anticompetitive agreement between participants on the same side in a market to buy or sell a product, service, or commodity only at a fixed price, or maintain the market conditions such that the price is maintained at a given level by controlling supply and demand. The intent of price fixing may be to push the price of a product as high as possible, generally leading to profits for all sellers but may also have the goal to fix, peg, discount, or stabilize prices.
ImpôtL'impôt constitue un des prélèvements obligatoires effectué par voie d’autorité par la puissance publique (l'État et les collectivités territoriales) sur les ressources des personnes vivant sur son territoire ou y possédant des intérêts. Ce prélèvement est destiné à être affecté par l'intermédiaire des budgets publics au financement de ressources (biens ou services) d'utilité générale.
Validity (statistics)Validity is the main extent to which a concept, conclusion or measurement is well-founded and likely corresponds accurately to the real world. The word "valid" is derived from the Latin validus, meaning strong. The validity of a measurement tool (for example, a test in education) is the degree to which the tool measures what it claims to measure. Validity is based on the strength of a collection of different types of evidence (e.g. face validity, construct validity, etc.) described in greater detail below.
Type dépendantEn Informatique et en Logique, un type dépendant est un type qui peut dépendre d'une valeur définie dans le langage typé. Les langages Agda et Gallina (de l'assistant de preuve Coq) sont des exemples de langages à type dépendant. Les types dépendants permettent par exemple de définir le type des listes à n éléments. Voici un exemple en Coq. Inductive Vect (A: Type): nat -> Type := | nil: Vect A 0 | cons (n: nat) (x: A) (t: Vect A n): Vect A (S n).
Information extractionInformation extraction (IE) is the task of automatically extracting structured information from unstructured and/or semi-structured machine-readable documents and other electronically represented sources. In most of the cases this activity concerns processing human language texts by means of natural language processing (NLP). Recent activities in multimedia document processing like automatic annotation and content extraction out of images/audio/video/documents could be seen as information extraction Due to the difficulty of the problem, current approaches to IE (as of 2010) focus on narrowly restricted domains.
Type systemIn computer programming, a type system is a logical system comprising a set of rules that assigns a property called a type (for example, integer, floating point, string) to every "term" (a word, phrase, or other set of symbols). Usually the terms are various constructs of a computer program, such as variables, expressions, functions, or modules. A type system dictates the operations that can be performed on a term. For variables, the type system determines the allowed values of that term.
Dépendance fonctionnelleEn théorie des bases de données relationnelles, une dépendance fonctionnelle est une contrainte entre deux ensembles d'attributs dans une relation (table) d'une base de données. Dans une relation R, on dit qu'il y a dépendance fonctionnelle entre un ensemble d'attributs A et un ensemble d'attributs B, ou que l'ensemble A d'attributs détermine l'ensemble B d'attributs (et on écrit A→B) si quand deux n-uplets coïncident sur leurs attributs A, alors ils coïncident aussi sur leurs attributs B.
