Krishnendu Gongopadhyay

  1. On the Conjugacy Classes in the orthogonal and symplectic groups over algebraically closed fields.

    Authors: Krishnendu Gongopadhyay
    Subjects: Group Theory
    Abstract

    Let $\F$ be an algebraically closed field. Let $\V$ be a vector space
    equipped with a non-degenerate symmetric or symplectic bilinear form $B$ over
    $\F$. Suppose the characteristic of $\F$ is \emph{large}, i.e. either zero or
    greater than the dimension of $\V$. Let $I(\V, B)$ denote the group of
    isometries. Using the Jacobson-Morozov lemma we give a new and simple proof of
    the fact that two elements in $I(\V,B)$ are conjugate if and only if they have
    the same elementary divisors.

  2. Topology of the conjugacy classes in Moebius groups.

    Authors: Krishnendu Gongopadhyay
    Subjects: Geometric Topology
    Abstract

    Let $H^{n+1}$ denote the $n + 1$-dimensional (real) hyperbolic space. Let
    $S^n$ denote the conformal boundary of the hyperbolic space. The group of
    conformal diffeomorphisms of $S^n$ is denoted by M(n). Let $M_o(n)$ be its
    identity component which consists of all orientation-preserving elements in
    M(n). The conjugacy classification of isometries in $M_o(n)$ depends on the
    conjugacy of $T$ and $T^{-1}$ in $M_o(n)$. For an element $T$ in M(n), $T$ and
    $T^{-1}$ are conjugate in M(n), but they may not be conjugate in $M_o(n)$.

  3. Algebraic Characterization of the Isometries of the Complex and Quaternionic Hyperbolic Plane.

    Authors: Wensheng Cao, Krishnendu Gongopadhyay
    Subjects: Geometric Topology
    Abstract

    Let $\F$ denote either of $\R$, $\C$ or the quaternions $\H$. Let $H^2_{\F}$
    denote the two dimensional hyperbolic space over $\F$. The algebraic
    characterization of the isometries of $H^2_{\R}$ and $H^3_{\R}$ in terms of
    their trace and determinant are foundational in the real hyperbolic geometry.
    The counterpart of this characterization for isometries of $H^2_{\C}$ was given
    by Giraud and Goldman. In this paper we offer algebraic characterization for
    the isometries of $H^2_{\H}$.

  4. Algebraic Characterization of the Isometries of the Complex and Quaternionic Hyperbolic Plane.

    Authors: Wensheng Cao, Krishnendu Gongopadhyay
    Subjects: Geometric Topology
    Abstract

    Let $\F$ denote either of $\R$, $\C$ or the quaternions $\H$. Let $H^2_{\F}$
    denote the two dimensional hyperbolic space over $\F$. The algebraic
    characterization of the isometries of $H^2_{\R}$ and $H^3_{\R}$ in terms of
    their trace and determinant are foundational in the real hyperbolic geometry.
    The counterpart of this characterization for isometries of $H^2_{\C}$ was given
    by Giraud and Goldman. In this paper we offer algebraic characterization for
    the isometries of $H^2_{\H}$.

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