Canonical

Science and technology

• Canonical form, a natural unique representation of an object, or a preferred notation for some object

Mathematics

• Canonical basis – Basis of a type of algebraic structure
• Canonical coordinates, sets of coordinates that can be used to describe a physical system at any given point in time
• Canonical map, a morphism that is uniquely defined by its main property
• Canonical polyhedron, a polyhedron whose edges are all tangent to a common sphere, whose center is the average of its vertices
• Canonical ring, a graded ring associated to an algebraic variety
• Canonical injection, in set theory
• Canonical representative, in set theory a standard member of each element of a set partition

Differential geometry

• Canonical one-form, a special 1-form defined on the cotangent bundle T*M of a manifold M
• Canonical symplectic form, the exterior derivative of this form
• Canonical vector field, the corresponding special vector field defined on the tangent bundle TM of a manifold M

Physics

• Canonical ensemble, in statistical mechanics, is a statistical ensemble representing a probability distribution of microscopic states of the system
• Canonical quantum gravity, an attempt to quantize the canonical formulation of general relativity
• Canonical stress–energy tensor, a conserved current associated with translations through space and time
• Canonical theory, a unified molecular theory of physics, chemistry, and biology
• Canonical conjugate variables, pairs of variables mathematically defined in such a way that they become Fourier transform duals
• Canonical transformation, in Hamiltonian mechanics
• Grand canonical ensemble, a probability distribution of microscopic states for an open system, which is being maintained in thermodynamic equilibrium
• Microcanonical ensemble, a theoretical tool used to analyze an isolated thermodynamic system

Computing

• Canonical Huffman code, a particular type of Huffman code with unique properties which allow it to be described in a very compact manner
• Canonical link element, an HTML element that helps webmasters prevent duplicate content issues by specifying the “canonical” or “preferred” version
• Canonical model, a design pattern used to communicate between different data formats
• Canonical name record (CNAME record), a type of Domain Name System record
• Canonical S-expressions, a binary encoding form of a subset of general S-expression
• Canonical XML, a normal form of XML, intended to allow relatively simple comparison of pairs of XML documents
• MAC address (formerly canonical number), a unique identifier assigned to network interfaces for communications on the physical network segment
• Canonicalization, a process for converting data to canonical form

Chemistry

• Canonical form, any of a set of representations of the resonance structure of a molecule each of which contributes to the real structure