• probability theory and ergodic theory, the invariant sigma-algebra is a sigma-algebra formed by sets which are invariant under a group action or dynamical system...
    10 KB (1,461 words) - 11:53, 27 July 2024
  • Thumbnail for Invariant (mathematics)
    the map T {\displaystyle T} is measurable, invariant sets form a sigma-algebra, the invariant sigma-algebra. The notion of invariance is formalized in...
    24 KB (2,787 words) - 13:39, 3 April 2025
  • {\displaystyle (X,\Sigma )} is said to be invariant under f {\displaystyle f} if, for every measurable set A {\displaystyle A} in Σ , {\displaystyle \Sigma ,} μ (...
    5 KB (852 words) - 19:30, 14 March 2025
  • Thumbnail for Projection (linear algebra)
    In linear algebra and functional analysis, a projection is a linear transformation P {\displaystyle P} from a vector space to itself (an endomorphism)...
    34 KB (5,806 words) - 14:46, 17 February 2025
  • viewpoint, the universal enveloping algebra of the Lie algebra of a Lie group may be identified with the algebra of left-invariant differential operators on the...
    51 KB (8,954 words) - 11:11, 9 February 2025
  • otherwise, a kind of invariant delta function on isomorphism classes of intervals. Its powers in the incidence algebra are the other invariant delta functions...
    18 KB (3,019 words) - 16:28, 26 May 2025
  • geometric algebra (also known as a Clifford algebra) is an algebra that can represent and manipulate geometrical objects such as vectors. Geometric algebra is...
    93 KB (13,801 words) - 22:00, 13 April 2025
  • mathematics, a Clifford algebra is an algebra generated by a vector space with a quadratic form, and is a unital associative algebra with the additional structure...
    65 KB (9,287 words) - 07:33, 12 May 2025
  • The scale-invariant feature transform (SIFT) is a computer vision algorithm to detect, describe, and match local features in images, invented by David...
    69 KB (9,232 words) - 19:22, 19 April 2025
  • v_{n}\mapsto v_{\sigma (1)}\otimes \cdots \otimes v_{\sigma (n)}} defines a linear endomorphism of Tn(V). A symmetric tensor is a tensor that is invariant under...
    13 KB (2,050 words) - 23:04, 2 March 2025
  • In mathematics, specifically algebraic geometry, Donaldson–Thomas theory is the theory of Donaldson–Thomas invariants. Given a compact moduli space of...
    10 KB (1,324 words) - 19:46, 17 December 2024
  • spacetime algebra (STA) is the application of Clifford algebra Cl1,3(R), or equivalently the geometric algebra G(M4) to physics. Spacetime algebra provides...
    48 KB (7,332 words) - 19:32, 1 May 2025
  • σ ) μ {\displaystyle ({\mathcal {J}}^{\rho \sigma })^{\mu }} . Similarly, since the equation is invariant under translations, there is a tensor of conserved...
    79 KB (13,120 words) - 13:01, 16 May 2025
  • Thumbnail for Quaternion
    Quaternion (category Composition algebras)
    -i\sigma _{1}=-\sigma _{2}\sigma _{3},\quad \mathbf {j} \mapsto -i\sigma _{2}=-\sigma _{3}\sigma _{1},\quad \mathbf {k} \mapsto -i\sigma _{3}=-\sigma _{1}\sigma...
    96 KB (12,665 words) - 22:22, 26 May 2025
  • In mathematical physics, the Dirac algebra is the Clifford algebra Cl 1 , 3 ( C ) {\displaystyle {\text{Cl}}_{1,3}(\mathbb {C} )} . This was introduced...
    15 KB (2,342 words) - 23:31, 7 April 2025
  • Choquet theory Hewitt–Savage zero–one law Krein–Milman theorem Invariant sigma-algebra Spiegelhalter, D. 2024 [1] Why probability doesn't exist (but it's...
    18 KB (2,571 words) - 11:09, 17 April 2025
  • abelian von Neumann algebras on separable Hilbert spaces, particularly since they are completely classifiable by simple invariants. Though there is a theory...
    10 KB (1,551 words) - 19:33, 9 February 2025
  • Gamma matrices (category Clifford algebras)
    }}{\begin{pmatrix}I_{2}&\sigma ^{2}\\\sigma ^{2}&-I_{2}\end{pmatrix}}~.} The Dirac algebra can be regarded as a complexification of the real algebra Cl1,3( R {\displaystyle...
    61 KB (7,254 words) - 20:44, 10 May 2025
  • Thumbnail for Lie algebra
    ]\otimes \mathrm {id} )\circ (\mathrm {id} +\sigma +\sigma ^{2})=0.} Affine Lie algebra Automorphism of a Lie algebra Frobenius integrability theorem (the integrability...
    61 KB (10,480 words) - 11:37, 29 May 2025
  • Thumbnail for Singular value decomposition
    Singular value decomposition (category Linear algebra)
    is invariant under unitary equivalence, this shows ‖ M ‖ = | ∑ i σ i 2 {\displaystyle \|\mathbf {M} \|={\sqrt {{\vphantom {\bigg |}}\sum _{i}\sigma _{i}^{2}}}}...
    91 KB (14,584 words) - 06:04, 19 May 2025
  • In physics, a sigma model is a field theory that describes the field as a point particle confined to move on a fixed manifold. This manifold can be taken...
    22 KB (4,143 words) - 19:08, 31 January 2025
  • Thumbnail for Poincaré group
    K_{j}\right]&=-i\hbar \epsilon _{ijk}L_{k}\end{aligned}}} The Casimir invariants of this algebra are P μ P μ {\textstyle P_{\mu }P^{\mu }} and W μ W μ {\textstyle...
    15 KB (2,173 words) - 11:07, 14 November 2024
  • Thumbnail for Lorentz group
    which provides a convenient alternative to the left-invariant vector field for calculating the Lie algebra. We can write down a set of six generators: Vector...
    66 KB (9,875 words) - 09:40, 29 May 2025
  • Thumbnail for Measure (mathematics)
    Σ {\displaystyle \Sigma } a σ-algebra over X . {\displaystyle X.} A set function μ {\displaystyle \mu } from Σ {\displaystyle \Sigma } to the extended...
    35 KB (5,559 words) - 12:21, 2 May 2025
  • Thumbnail for Spinor
    {\displaystyle (-1)\{a_{1}\sigma _{1}+a_{2}\sigma _{2}\}\,(-1)=a_{1}\sigma _{1}+a_{2}\sigma _{2}} but a spinor rotation of 180°. The Clifford algebra Cℓ3,0( R {\displaystyle...
    72 KB (9,924 words) - 15:56, 26 May 2025
  • Thumbnail for Standard deviation
    represented in mathematical texts and equations by the lowercase Greek letter σ (sigma), for the population standard deviation, or the Latin letter s, for the...
    59 KB (8,233 words) - 19:16, 23 April 2025
  • Categorical quotient (category Algebraic geometry)
    that (i) is invariant; i.e., π ∘ σ = π ∘ p 2 {\displaystyle \pi \circ \sigma =\pi \circ p_{2}} where σ : G × X → X {\displaystyle \sigma :G\times X\to...
    2 KB (279 words) - 20:45, 12 August 2023
  • ν ] {\displaystyle \sigma ^{\mu \nu }={\frac {i}{2}}\left[\gamma ^{\mu },\gamma ^{\nu }\right]} This then gives the full algebra [ M μ ν , Q α ] = 1 2...
    17 KB (2,744 words) - 03:19, 22 March 2025
  • Arf invariant of a certain quadratic form on H 1 ( Σ , Z / 2 Z ) {\displaystyle H_{1}(\Sigma ,\mathbb {Z} /2\mathbb {Z} )} . This Arf invariant is obviously...
    10 KB (1,517 words) - 17:15, 21 December 2023
  • Ring theory (category Algebraic structures)
    In algebra, ring theory is the study of rings, algebraic structures in which addition and multiplication are defined and have similar properties to those...
    24 KB (3,093 words) - 14:02, 18 May 2025