Now showing items 1-20 of 55

    • Markovianity and the Thompson Group F (Pre-published version) 

      Koestler, Claus; Krishnan, Arundhathi (2022-10-27)
      We show that representations of the Thompson group F in the automorphisms of a noncommutative probability space yield a large class of bilateral stationary noncommutative Markov processes. As a partial converse, bilateral ...
    • Pseudospectrum of an element of a Banach algebra (Pre-published version) 

      Kulkarni, S H; Krishnan, Arundhathi (Element Publishing House, 2017-03)
      The ε -pseudospectrum Λε (a) of an element a of an arbitrary Banach algebra A is studied. Its relationships with the spectrum and numerical range of a are given. Characterizations of scalar, Hermitian and Hermitian idempotent ...
    • Pseudospectra of elements of reduced Banach algebras (Pre-published version) 

      Kulkarni, S H; Krishnan, Arundhathi (Springer, 2017)
      Let A be a Banach algebra with identity 1 and p ∈ A be a non-trivial idempotent. Then q = 1−p is also an idempotent. The subalgebras pAp and qAq are Banach algebras, called reduced Banach algebras, with identities p and q ...
    • Markovianity and the Thompson monoid F+ (Pre-published version) 

      Koestler, Claus; Krishnan, Arundhathi; Wills, Stephen (Elsevier, 2023-03-13)
      We introduce a new distributional invariance principle, called `partial spreadability', which emerges from the representation theory of the Thompson monoid F+ in noncommutative probability spaces. We show that a partially ...
    • Pseudospectra of elements of reduced Banach algebras II (Pre-published version) 

      Kulkarni, S H; Krishnan, Arundhathi (Faculty of Sciences and Mathematics, University of Nis, Serbia, 2018-06)
      Let A be a Banach algebra with identity 1 and p ∈ A be a non-trivial idempotent. Then q = 1 − p is also an idempotent. The subalgebras pAp and qAq are Banach algebras, called reduced Banach algebras, with identities p and ...
    • Which graphs are rigid in lpd? (Pre-published) 

      Dewar, Sean; Kitson, Derek; Nixon, Anthony (Springer, 2021-03-13)
      We present three results which support the conjecture that a graph is minimally rigid in d-dimensional ℓp-space, where p∈(1,∞) and p≠2, if and only if it is (d, d)-tight. Firstly, we introduce a graph bracing operation ...
    • The stability space of the derived category of holomorphic triples and further investigations 

      Rüffer, Arne (2021-04-14)
      In this thesis we give a complete description of the Bridgeland stability space for the bounded derived category of holomorphic triples over a smooth projective curve of genus one as a connected, four dimensional complex ...
    • Constructing isostatic frameworks for the l1 and l infinity plane (Pre-published) 

      Clinch, Katie; Kitson, Derek (Electronic Journal of Combinatorics, 2020-06-12)
      We use a new coloured multi-graph constructive method to prove that if the edge-set of a graph G = (V,E) has a partition into two spanning trees T1 and T2 then there is a map p : V → R2, p(v) = (p(v)1,p(v)2), such that ...
    • Graph rigidity for unitarily invariant matrix norms (Pre-published) 

      Kitson, Derek; Levene, Rupert H (Elsevier, 2020-11-15)
      A rigidity theory is developed for bar-joint frameworks in linear matrix spaces endowed with a unitarily invariant matrix norm. Analogues of Maxwell's counting criteria are obtained and minimally rigid matrix frameworks ...
    • Symbol functions for symmetric frameworks (Pre-published) 

      Kitson, Derek; Kastis, Eleftherios; McCarthy, John E (Elsevier, 2021-05-15)
      We prove a variant of the well-known result that intertwiners for the bilateral shift on ℓ2(Z) are unitarily equivalent to multiplication operators on L2(T). This enables us to unify and extend fundamental aspects of ...
    • Rigidity of symmetric frameworks in normed spaces 

      Kitson, Derek; Nixon, Anthony; Schulze, Bernd (Elsevier, 2020-12-15)
      We develop a combinatorial rigidity theory for symmetric bar-joint frameworks in a general finite dimensional normed space. In the case of rotational symmetry, matroidal Maxwell-type sparsity counts are identified for a ...
    • Symmetric powers of trace forms on symbol algebras 

      Flatley, Ronan (Université D'Artois, 2013)
    • Anomalies of the magnitude of the bias of the maximum likelihood estimator of the regression slope 

      O'Driscoll, Diarmuid; Ramirez, Donald E. (Athens Institute for Education and Research, 2015)
      The slope of the best-fit line y h x x 0 1  ( )    from minimizing a function of the squared vertical and horizontal errors is the root of a polynomial of degree four which has exactly two real roots, one positive and ...
    • An investigation of the performance of five different estimators in the measurement error regression model 

      O'Driscoll, Diarmuid; Ramirez, Donald E. (Athens Institute for Education and Research, 2015)
      In a comprehensive paper by Riggs et al.(1978) the authors analyse the performances of numerous estimators for the regression slope in the measurement error model with positive measurement error variances >0 0 for X and ...
    • On moduli stacks of G-bundles over a curve (Pre-published version) 

      Hoffmann, Norbert (Springer, 2010)
      Let C be a smooth projective curve over an algebraically closed eld k of arbitrary characteristic. Given a linear algebraic group G over k, let MG be the moduli stack of principal G-bundles on C. We determine the set of ...
    • Moduli stacks of vector bundles on curves and the King–Schofield rationality proof (Pre-published version) 

      Hoffmann, Norbert (Springer, 2010)
      Let C be a connected smooth projective curve of genus g ≥ 2 over an algebraically closed field k. Consider the coarse moduli scheme Bunr,d (resp. Bunr,L) of stable vector bundles on C with rank r and degree d ∈ Z (resp. ...
    • On semistable vector bundles over curves (Pre-published version) 

      Hoffmann, Norbert; Biswas, Indranil; Hein, Georg (Elsevier, 2008)
      Let X be a geometrically irreducible smooth projective curve de ned over a eld k, and let E be a vector bundle on X. Then E is semistable if and only if there is a vector bundle F on X such that Hi(X; F E) = 0 for i = 0; ...
    • Poincaré families and automorphisms of principal bundles on a curve (Pre-published version) 

      Hoffmann, Norbert; Biswas, Indranil (Elsevier, 2009)
      Let C be a smooth projective curve, and let G be a reductive algebraic group. We give a necessary condition, in terms of automorphism groups of principal G-bundles on C, for the existence of Poincaré families parameterized ...
    • Moment estimation of measurement errors 

      O'Driscoll, Diarmuid; Ramirez, Donald E. (NEDETAS, 2011)
      The slope of the best-fit line from minimizing a function of the squared vertical and horizontal errors is the root of a polynomial of degree four. We use second order and fourth order moment equations to estimate the ratio ...
    • Revisiting some design criteria 

      O'Driscoll, Diarmuid; Ramirez, Donald E. (Athens Institute for Education and Research, 2015)
      We address the problem that the A (trace) design criterion is not scale invariant and often is in disagreement with the D (determinant) design criterion. We consider the canonical moment matrix CM and use the trace of its ...