Continuum theory 1970-01-01
Continuum theory is a branch of mathematics that deals with the properties and structures of continua, which can be understood as "continuous" sets. The most common context for discussing continuum theory is in topology, where it often focuses on the study of spaces that are connected and compact, such as the real number line or various types of geometrical shapes.
Separation axioms 1970-01-01
Separation axioms are a set of conditions in topology that describe how distinct points and sets can be "separated" from each other using open sets. These axioms help to classify topological spaces based on their separation properties. The different separation axioms build upon each other, and they include: 1. **T0 (Kolmogorov)**: A space is T0 if for any two distinct points, there exists an open set containing one of the points but not the other.
Adherent point 1970-01-01
An **adherent point** is a concept in topology, a branch of mathematics. In the context of a topological space, an adherent point (or limit point) of a set refers to a point that is either in the set itself or is a limit point of that set.
Appert topology 1970-01-01
Appert topology is a concept in the field of topology, specifically a type of topology on a set that is defined via a particular collection of open sets. The Appert topology is based on the idea of "approximating" the standard topology of a topological space through certain properties.
Axiom of countability 1970-01-01
The Axiom of Countability is a principle in set theory that deals with the properties of countable sets. In the context of set theory, a set is considered countable if it can be put into a one-to-one correspondence with the set of natural numbers (i.e., it can be enumerated). Specifically, the Axiom of Countability generally refers to the notion that certain mathematical structures possess countable bases or countable properties.
Base (topology) 1970-01-01
Boundary (topology) 1970-01-01
Cauchy space 1970-01-01
A **Cauchy space** is a concept from the field of topology and analysis, named after the mathematician Augustin-Louis Cauchy. It generalizes certain properties of sequences and convergence in metric spaces, allowing for a more abstract setting in which to study convergence and completeness. In more formal terms, a **Cauchy space** is defined in the following way: 1. **Set and Filter**: Start with a set \( X \).
Clopen set 1970-01-01
In topology, a set is called **clopen** if it is both **closed** and **open**. To understand this concept, we need to clarify what it means for a set to be open and closed: 1. A set \( U \) in a topological space is **open** if, for every point \( x \) in \( U \), there exists a neighborhood of \( x \) that is entirely contained within \( U \).
Closed set 1970-01-01
In topology, a **closed set** is a fundamental concept related to the structure of a topological space. A subset \( C \) of a topological space \( X \) is called closed if it contains all its limit points. Here are some important properties and characteristics of closed sets: 1. **Complement**: A set is closed if its complement (with respect to the whole space \( X \)) is open.
Closeness (mathematics) 1970-01-01
In mathematics, "closeness" often refers to a concept related to the distance between points, objects, or values in a particular space. It can be defined in various contexts, such as in metric spaces, topology, and real analysis.
Closure (topology) 1970-01-01
In topology, the **closure** of a set refers to a fundamental concept related to the limit points and the boundary of that set within a given topological space. Specifically, the closure of a set \( A \) in a topological space \( (X, \tau) \) is the smallest closed set that contains \( A \).
Cocountable topology 1970-01-01
Cocountable topology is a specific type of topology defined on a set where a subset is considered open if it is either empty or its complement is a countable set. More formally, let \( X \) be a set. The cocountable topology on \( X \) is defined by specifying that the open sets are of the form \( U \subseteq X \) such that either: 1. \( U = \emptyset \), or 2.
Cofiniteness 1970-01-01
Cofiniteness is a concept often discussed in the context of model theory and formal languages, particularly related to the properties of certain mathematical structures. In general, a property or structure is said to exhibit cofiniteness when the complement set (or the set of elements that do not belong to it) is finite.
Coherent topology 1970-01-01
Coherent topology is a type of topology that is often used in the context of sheaf theory and algebraic geometry, particularly to study the behavior of sheaves over topological spaces. It is commonly associated with coherent sheaves, which are a particular type of sheaf that can be thought of as a generalization of vector bundles or modules over a ring.
Compact-open topology 1970-01-01
The compact-open topology is a topology defined on the space of continuous functions between topological spaces, particularly when considering the set of continuous functions from one topological space to another. This topology is especially useful in areas like functional analysis and algebraic topology.
Comparison of topologies 1970-01-01
The comparison of topologies generally refers to the process of analyzing and contrasting different topological structures on a set. In the context of topology, this involves examining how various topologies can be defined on the same set and how they relate to one another in terms of properties and behavior.
Completely metrizable space 1970-01-01
A completely metrizable space is a topological space that can be given a metric (or distance function) such that the topology induced by this metric is the same as the original topology of the space, and furthermore, the metric is complete. To break this down: 1. **Topological Space**: This is a set of points, along with a collection of open sets that satisfy certain axioms (like closure under unions and finite intersections).
Completely uniformizable space 1970-01-01
A completely uniformizable space is a type of topological space that can be endowed with a uniform structure such that the uniform structure defines a topology that is equivalent to the original topology of the space. In more detail, a uniform space is a set equipped with a filter of entourages that allows us to talk about concepts such as "uniform continuity" and "Cauchy sequences.
Connected space 1970-01-01
In topology, a connected space is a fundamental concept that refers to a topological space that cannot be divided into two disjoint, non-empty open sets. More formally, a topological space \( X \) is called connected if there do not exist two open sets \( U \) and \( V \) such that: 1. \( U \cap V = \emptyset \) 2. \( U \cup V = X \) 3.