Nico Spronk

ORCID: 0000-0002-0413-516X
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Research Areas
  • Advanced Operator Algebra Research
  • Advanced Topics in Algebra
  • Holomorphic and Operator Theory
  • Algebraic structures and combinatorial models
  • Advanced Banach Space Theory
  • Spectral Theory in Mathematical Physics
  • Advanced Algebra and Geometry
  • Mathematical Analysis and Transform Methods
  • Noncommutative and Quantum Gravity Theories
  • Matrix Theory and Algorithms
  • Advanced Mathematical Physics Problems
  • advanced mathematical theories
  • Rings, Modules, and Algebras
  • semigroups and automata theory
  • Quantum Chromodynamics and Particle Interactions
  • Advanced Harmonic Analysis Research
  • Advanced Differential Geometry Research
  • Advanced Mathematical Modeling in Engineering
  • Homotopy and Cohomology in Algebraic Topology
  • Geometric and Algebraic Topology
  • Finite Group Theory Research

University of Waterloo
2011-2022

Carleton University
2008

University of Illinois Urbana-Champaign
2008

Regional Municipality of Waterloo
2007

Texas A&M University
2002-2004

Let G be a locally compact group, L p ( ) the usual ‐space for 1 ⩽ ∞, and A( Fourier algebra of . Our goal is to study, in new abstract context, completely bounded multipliers ), which we denote M cb ). We show that can characterised as ‘invariant part’ space (completely) normal ∞ )‐bimodule maps on B(L 2 )), operators In doing this develop function‐theoretic description X , μ)‐bimodule μ)), by V μ), name measurable Schur μ). approach leads many results, some generalise results hitherto...

10.1112/s0024611504014650 article EN Proceedings of the London Mathematical Society 2004-06-30

10.1016/j.jfa.2004.11.011 article EN publisher-specific-oa Journal of Functional Analysis 2005-03-04

Abstract We investigate generalized amenability and biflatness properties of various (operator) Segal algebras in both the group algebra, L 1 ( G ), Fourier A a locally compact .

10.4153/cjm-2010-044-4 article EN Canadian Journal of Mathematics 2010-05-20

We show that for any locally compact group $G$, the Fourier algebra $\mathrm {A}(G)$ is operator weakly amenable.

10.1090/s0002-9939-02-06680-7 article EN Proceedings of the American Mathematical Society 2002-06-11

Let $G$ be a locally compact group. It is shown that there exists natural completely isometric representation of the bounded Fourier multiplier algebra $M_{cb}A(G)$, which dual to measure $M(G)$, on $\mathcal {B}(L_2(G))$. The image algebras $M(G)$ and $M_{cb}A(G)$ in {CB}^{\sigma } (\mathcal {B}(L_2(G)))$ are intrinsically characterized, some commutant theorems proved. also for any amenable group $G$, $UCB(\hat G)^*$ {B}(L_2(G))$, can regarded as duality result Neufang's theorem $LUC(G)^*$.

10.1090/s0002-9947-07-03940-2 article EN Transactions of the American Mathematical Society 2007-11-20

We study two related questions. (1) For a compact group $G$, what are the ranges of convolution maps on $\mathrm{A}(G\times G)$ given for $u,v$ in $\mathrm{A}(G)$ by $u\times v\mapsto u\ast\check{v}$ ($\check{v}(s)=v(s^{-1})$) and u

10.4064/sm196-3-2 article EN Studia Mathematica 2010-01-01

We investigate, for a locally compact group $G$, the operator amenability of Fourier–Stieltjes algebra $B(G)$ and reduced $B_r(G)$. The natural conjecture is that any these algebras amenable if only $G$ compact. partially prove this with mere replaced by $C$-amenability some constant $C\,{<}\, 5$. In process, we obtain new decomposition $B(G)$, which can be interpreted as non-commutative counterpart $M(G)$ into discrete continuous measures. further introduce variant – called...

10.1017/s030500410300745x article EN Mathematical Proceedings of the Cambridge Philosophical Society 2004-04-21

Let G be a compact group and C(G) the C*-algebra of continuous complex-valued functions on G. The paper constructs an imbedding Fourier algebra A(G) into V(G) = C(G)⊗hC(G) (Haagerup tensor product) deduces results about parallel spectral synthesis, generalizing result Varopoulos. It then characterizes which diagonal sets in × are operator synthesis with respect to Haar measure, using definition due Arveson. This is applied obtain analogue Froelich: formula for algebras associated pre-orders...

10.1112/s0024610702003356 article EN Journal of the London Mathematical Society 2002-10-01

Abstract Let G be a locally compact group, and let A cb ( ) denote the closure of ), Fourier algebra , in space completely boundedmultipliers ). If is weakly amenable, discrete group such that C *( residually finite-dimensional, we show operator amenable. In particular, amenable even though free two generators, not an group. Moreover, if closed ideal complemented only it has approximate identity bounded cb-multiplier norm.

10.4153/cjm-2007-041-9 article EN Canadian Journal of Mathematics 2007-10-01

10.1112/blms/bdl026 article EN Bulletin of the London Mathematical Society 2007-02-09

We give for a compact group G, full characterization of when its Fourier algebra A(G) is weakly amenable: the connected component identity G e abelian. This condition also equivalent to hyper-Tauberian property A(G), and having anti-diagonal Δ = {(s,s -1 ): S ∈ G} be set spectral synthesis A(GxG). extend our results some classes non-compact, locally groups, including small invariant neighbourhood groups maximally almost periodic groups. close by illustrating curious relationship between...

10.1512/iumj.2009.58.3762 article EN Indiana University Mathematics Journal 2009-01-01

10.1016/j.jfa.2011.09.017 article EN publisher-specific-oa Journal of Functional Analysis 2011-10-07

10.1016/j.jfa.2016.03.008 article EN Journal of Functional Analysis 2016-03-23

Let $G$ be a locally compact group. It is not always the case that its reduced C*-algebra $C^*_r(G)$ admits tracial state. We exhibit closely related necessary and sufficient conditions for existence of such. gain complete answer when compactly generated. In particular almost connected, or more generally nuclear, trace equivalent to amenability. two examples classes totally disconnected groups which does admit

10.48550/arxiv.1706.05354 preprint EN other-oa arXiv (Cornell University) 2017-01-01

We study, for a locally compact group $G$, the compactifications $(\pi,G^\pi)$ associated with unitary representations $\pi$, which we call {\it $\pi$-Eberlein compactifications}. also study Gelfand spectra $\Phi_{\mathcal{A}}(\pi)}$ of uniformly closed algebras $\mathcal{A}(\pi)$ generated by matrix coefficients such $\pi$. note that $\Phi_{\mathcal{A}(\pi)}\cup\{0\}$ is itself semigroup and show Silov boundary $G^\pi$. containment relations various coefficients, give new characterisation...

10.1512/iumj.2013.62.4825 article EN Indiana University Mathematics Journal 2013-01-01

10.1016/s0022-1236(03)00169-1 article EN publisher-specific-oa Journal of Functional Analysis 2003-09-03

Let $G$ be a locally compact group, $\mathrm{A}(G)$ its Fourier algebra and $\mathrm{L}^1(G)$ the space of Haar integrable functions on $G$. We study Segal ${\mathrm{S}^1\!\mathrm{A}(G)}= {\mathrm{A}(G)}\cap{\rm L}^1(G)$ in ${\mathrm{A}(G)}$.

10.4064/sm179-3-5 article EN Studia Mathematica 2007-01-01

10.1112/plms/pdl002 article EN Proceedings of the London Mathematical Society 2006-11-27

Let<inline-formula content-type="math/mathml"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper G"><mml:semantics><mml:mi>G</mml:mi><mml:annotation encoding="application/x-tex">G</mml:annotation></mml:semantics></mml:math></inline-formula>be a compact connected Lie group. The question of when weighted Fourier algebra on<inline-formula encoding="application/x-tex">G</mml:annotation></mml:semantics></mml:math></inline-formula>is completely isomorphic to an operator will...

10.1090/tran6653 article EN publisher-specific-oa Transactions of the American Mathematical Society 2015-03-04

Abstract Let G be a finitely generated group with polynomial growth, and let ω weight, i.e. sub-multiplicative function on positive values. We study when the weighted algebra ℓ 1 ( G, ) is isomorphic to an operator algebra. show that if weight large enough degree or exponential of order 0 &lt; α 1. demonstrate growth plays important role in this problem. Moreover, algebraic centre Q -algebra, hence satisfies multi-variable von Neumann inequality. also present more detailed our results...

10.1017/s0013091514000212 article EN Proceedings of the Edinburgh Mathematical Society 2015-01-05

10.1016/j.jfa.2007.03.028 article EN publisher-specific-oa Journal of Functional Analysis 2007-05-16
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