|  Non-Commutative Geometry | 
In General
  > s.a. manifolds / holonomy;
  quantum group; Spectral Triple;
  Star Product.
  * Idea: Non-commutative spaces are
    spaces with quantum group symmetry; They are based on (1) A non-commutative algebra
    \(\cal A\) defined by a star product which replaces the Abelian one of functions
    on a manifold, with a representation on a Hilbert space \(\cal H\); (2) An exterior
    differential algebra on Ω( \(\cal A\)), (n+1)-forms; (3) Possibly some
    additional structure, like a Dirac operator, which encodes the metric structure.
  * History: A precursor was Snyder's
    spacetime in which coordinates are operators with commutation relations of the form
    [xμ, xν]
    = i q2θμν;
    > s.a. quantum spacetime.
Examples and Other Structures > s.a. non-commutative cosmology,
   gravity [black holes], spacetime [including causality].
  * Example: The commutation relations
    between coordinates become [xm,
    xn]
    = i θmn,
    where θmn
    is a (constant) real antisymmetric matrix.
  * Symmetries: Lie algebra
    symmetries are replaced by Hopf algebra symmetries.
  @ Spheres: Madore CQG(97)gq;
    Pinzul & Stern PLB(01)ht
      [S2q, Dirac operator];
    Sitarz LMP(01)mp,
    CMP(03)mp/01 [S4];
    Freidel & Krasnov JMP(02) [star-product];
    Connes & Dubois-Violette LMP(03),
    CMP(08)m.QA/05 [S3];
    Lizzi et al JMP(05) [symmetries];
    Dąbrowski JGP(06)
      [S2q
      and S3q];
    Govindarajan et al JPA(10)-a0906 [polynomial deformations of fuzzy spheres];
    D'Andrea et al LMP(13);
    Berenstein et al a1506 [rotating fuzzy spheres];
    Ishiki & Matsumoto a1904 [diffeomorphisms of fuzzy spheres];
    > s.a. spherical harmonics.
  @ Moyal / Groenewold-Moyal plane:
    Amelino-Camelia et al a0812 [distance observable];
    Balachandran et al a0905-conf,
    Balachandran & Padmanabhan a0908-proc,
    Balachandran et al FP(10) [causality, statistics and other effects];
    Cagnache et al JGP(11)-a0912 [geometry];
    Acharyya & Vaidya JHEP(10)-a1005 [accelerated observers];
    Isidro et al AMP(11)-a1007 [commutator algebra];
    Martinetti & Tomassini CMP(13)-a1110 [and spectral distance between coherent states],
    a1205-proc [length and distance];
    > s.a.  non-commutative gauge theory [QED];
      types of quantum field theories.
  @ Other examples:
    Dimakis & Müller-Hoissen phy/97;
    Cerchiai et al EPJC(99)m.QA/98 [q-deformed line];
    Connes & Dubois-Violette CMP(02)m.QA/01 [3D spherical manifolds];
    Jackiw NPPS(02)ht/01 [physical];
    Alexanian et al JGP(02) [\(\mathbb C\)P2];
    Fiore et al JMP(02) [real quantum plane];
    van Suijlekom JMP(04)mp/03 [Lorentzian cylinder];
    Lubo PRD(05)ht/04 [star product on fuzzy sphere from squeezed state];
    Burić & Madore ht/04-conf [2D, review],
    PLB(05) [2D, example];
    Gromov a1002 [quantum analogs of constant-curvature spaces];
    D'Andrea et al Sigma(14)-a1406 [from deformations of canonical commutation relations];
    > s.a. classical particles; deformed minkowski
      space; rindler space; schwarzschild spacetime.
  @ Manifolds with boundary: Iochum & Levy JFA(10)-a1001;
    Belishev & Demchenko JGP(14)-a1306 [recovering the manifold from boundary data].
  @ Tensor fields / calculus: Dubois-Violette qa/95 [derivations, connections];
    Dvoeglazov S&S(02)mp,
    in(03)mp [derivatives];
    Dimitrijević et al JPA(04) [κ-deformed euclidean space];
    Vassilevich CQG(10) [tensor calculus];
    > s.a. exterior calculus.
  @ Symmetries: Agostini et al IJMPA(04)ht/03 [Hopf algebra];
    Calmet PRD(05);
    Chaichian et al PRL(05) [twisted Poincaré symmetry];
    Gonera et al PRD(05)ht [global];
    Gracia-Bondía et al PRD(06);
    Szabo CQG(06) [rev, and gravity];
    Goswami CMP(09)-a0704;
    Banica & Goswami CMP(10) [new examples of non-commutative spheres];
    Murray & Govaerts PRD(11)-a1008,
    Burić & Madore EPJC(14)-a1401 [spherically symmetric spaces].
  @ Related topics:
    Breslav & Zapatrin IJTP(00) [quantum/Greechie logic];
    Díaz & Pariguán JPA(07)mp/06 [measures and path integration];
    Carey et al a0901,
    Schenkel & Uhlemann Sigma(13)-a1308 [Dirac operators];
    Berest et al a1202 [non-commutative Poisson structures];
    > s.a. loop group; principal fiber bundles;
      diffeomorphisms.
References > s.a. affine connections;
  C*-algebras; differential geometry
  [fuzzy]; models of topology change.
  @ Texts and reviews: Manin 91;
    Connes 94;
    Madore 95 [connection and curvature],
    gq/99-ln;
    Landi LNP-ht/97;
    Várilly phy/97-ln;
    Bigatti ht/98;
    Madore 99;
    Connes JMP(00)ht,
    m.QA/00;
    Martinetti ht/06-proc;
    Kar 08 [pedagogical, strings and quantum field theory];
    Petitot a1505-in [rev];
    Majid in Bullett et al 17;
    Connes a1910 [developments];
    Lupercio NAMS-a2008 [short intro].
  @ General:
    Connes CRAS(80)ht/01;
    Dubois-Violette CRAS(88),
    et al JMP(90) [matrix algebras];
    Coquereaux JGP(89),
    JGP(93);
    Connes LMP(95),
    JMP(95);
    Kisil in(99)fa/97 [approaches];
    Dimakis & Madore JMP(96) [differential calculi];
    Jackiw & Pi PRL(02)ht/01 [coordinate changes];
    Rennie & Várilly m.OA/06 [manifold reconstruction];
    Chaichian et al JMP(08)ht/06 [Riemannian, framework];
    Piacitelli AIP(09)-a0901;
    Lord et al JGP(12) [Riemannian manifolds];
    Martinetti et al RVMP(12)-a1201 [minimal length];
    Barrett et al JPA(19)-a1902 [extracting information from the spectrum of the Dirac operator];
    Huggett et al a2006 [points cannot be defined].
  @ Almost commutative geometry: Madore RPMP(99)gq/97 [Poisson structure and curvature];
    Jureit & Stephan JMP(05),
    Jureit et al JMP(05) [classification];
    Kuntner & Steinacker JGP(12) [semiclassical limit, metric-compatible Poisson structures];
    Boeijink & van den Dungen JMP(14)-a1405.
  @ Categorical approach: Bertozzini et al a0801-proc,
    JPCS(12)-a1409;
    Bertozzini a1412-proc
      [relational quantum theory and emergent spacetime].
  @ Spectral distance: Wallet RVMP(12)-a1112 [examples];
    D'Andrea & Martinetti a1807 [dual formula];
    > s.a. spectral geometry;
      Mathematical Garden page.
  @ Curvature: Madore CJP(97)gq/96 [and connection];
    Dubois-Violette  et al JMP(96);
    Floricel et al JNCG-a1612 [Ricci curvature];
    Fathizadeh & Khalkhali a1901-fs [recent developments].
  @ Related topics: Dimakis & Müller-Hoissen JMP(99)gq/98 [discrete];
    Lord mp/00-wd;
    Martinetti PhD(01)mp [distances];
    Ponge LMP(08) ["lower-dimensional" volumes];
    Wagner PLMS(13)-a1108 [smooth localization method];
    D'Andrea & Martinetti LMP(12)-a1203,
    D'Andrea a1507-proc [Pythagoras' theorem];
    Barrett & Glaser JPA(16)-a1510,
    Glaser JPA(17)-a1612 [random non-commutative geometries, simulations, critical behavior];
    Glaser & Stern a1912
      [effect of a spectral cut-off on Riemannian manifolds];
    Khalkhali & Pagliaroli a2006 [phase transition].
  @ Generalizations: Vacaru mp/02-ch,
    mp/02-ch [Finsler, with local anisotropy];
    Kalyanapuram a1806.
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