MATHEMATICA SCANDINAVICA
http://www.mscand.dk/
Published by Mathematica Scandinavicaen-USMATHEMATICA SCANDINAVICA0025-5521<p>Submission of manuscripts implies that the work described has not been published before (except in the form of an abstract or as part of a published lecture, review or thesis), that it is not under consideration for publication elsewhere and that, if and when the manuscript is accepted for publication, the authors agree to automatic transfer of the copyright to the publisher. Authors may submit manuscripts for publication to any member of the editorial committee.</p><p> </p>Edgewise Cohen-Macaulay connectivity of partially ordered sets
http://www.mscand.dk/article/view/97270
<p>The proper parts of face lattices of convex polytopes are shown to satisfy a strong form of the Cohen-Macaulay property, namely that removing from their Hasse diagram all edges in any closed interval results in a Cohen-Macaulay poset of the same rank. A corresponding notion of edgewise Cohen-Macaulay connectivity for partially ordered sets is investigated. Examples and open questions are discussed.</p>Christos A. AthanasiadisMyrto Kallipoliti
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-20122151710.7146/math.scand.a-97270On the $x$-coordinates of Pell equations which are Fibonacci numbers
http://www.mscand.dk/article/view/97271
<p>For an integer $d>2$ which is not a square, we show that there is at most one value of the positive integer $x$ participating in the Pell equation $x^2-dy^2=\pm 1$ which is a Fibonacci number.</p>Florian LucaAlain Togbé
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-201221183010.7146/math.scand.a-97271A global Briançon-Skoda-Huneke-Sznajdman theorem
http://www.mscand.dk/article/view/97253
<p>We prove a global effective membership result for polynomials on a non-reduced algebraic subvariety of $\mathbb{C}^N$. It can be seen as a global version of a recent local result of Sznajdman, generalizing the Briançon-Skoda-Huneke theorem for the local ring of holomorphic functions at a point on a reduced analytic space.</p>Mats Andersson
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-201221315210.7146/math.scand.a-97253Automorphisms of the moduli space of principal $G$-bundles induced by outer automorphisms of $G$
http://www.mscand.dk/article/view/26348
<p>In this work we study finite-order automorphisms of the moduli space of principal $G$-bundles coming from outer automorphisms of the structure group when $G$ is a simple complex Lie group. We do this by describing the subvarieties of fixed points for the action of that automorphisms on the moduli space of principal $G$-bundles. In particular, we prove that these fixed points are reductions of structure group to the subgroup of fixed points of the outer automorphism. Moreover, we study the way in which these fixed points fall into the stable or nonstable locus of the moduli.</p>Álvaro Antón Sancho
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-201221538310.7146/math.scand.a-26348Unbounded symmetric analytic functions on $\ell_1$
http://www.mscand.dk/article/view/102082
<p>We show that each $G$-analytic symmetric function on an open set of $\ell _1$ is analytic and construct an example of a symmetric analytic function on $\ell _1$ which is not of bounded type.</p>Iryna ChernegaAndriy Zagorodnyuk
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-201221849010.7146/math.scand.a-102082Cuntz Splice invariance for purely infinite graph algebras
http://www.mscand.dk/article/view/96633
<p>We show that the Cuntz Splice preserves the stable isomorphism class of a purely infinite graph $\mathrm{C}^*$-algebra with finitely many ideals.</p>Rasmus Bentmann
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-2012219110610.7146/math.scand.a-96633Propagation of polynomial phase space singularities for Schrödinger equations with quadratic Hamiltonians
http://www.mscand.dk/article/view/97187
<p>We study propagation of phase space singularities for a Schrödinger equation with a Hamiltonian that is the Weyl quantization of a quadratic form with non-negative real part. Phase space singularities are measured by the lack of polynomial decay of given order in open cones in the phase space, which gives a parametrized refinement of the Gabor wave front set. The main result confirms the fundamental role of the singular space associated to the quadratic form for the propagation of phase space singularities. The singularities are contained in the singular space, and propagate in the intersection of the singular space and the initial datum singularities along the flow of the Hamilton vector field associated to the imaginary part of the quadratic form.</p>Patrik Wahlberg
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-20122110714010.7146/math.scand.a-97187Composition operators on weighted spaces of holomorphic functions on the upper half plane
http://www.mscand.dk/article/view/97126
<p>We consider moderately growing weight functions $v$ on the upper half plane $\mathbb G$ called normal weights which include the examples $(\mathrm{Im} w)^a$, $w \in \mathbb G$, for fixed $a > 0$. In contrast to the comparable, well-studied situation of normal weights on the unit disc here there are always unbounded composition operators $C_{\varphi }$ on the weighted spaces $Hv(\mathbb G)$. We characterize those holomorphic functions $\varphi \colon \mathbb G \rightarrow \mathbb G$ where the composition operator $C_{\varphi } $ is a bounded operator $Hv(\mathbb G) \rightarrow Hv(\mathbb G)$ by a simple property which depends only on $\varphi $ but not on $v$. Moreover we show that there are no compact composition operators $C_{\varphi }$ on $Hv(\mathbb G)$.</p>Wolfgang Lusky
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-20122114115010.7146/math.scand.a-97126Woronowicz Tannaka-Krein duality and free orthogonal quantum groups
http://www.mscand.dk/article/view/97320
<p>Given a finite-dimensional Hilbert space $H$ and a collection of operators between its tensor powers satisfying certain properties, we give a short proof of the existence of a compact quantum group $G$ with a fundamental representation $U$ on $H$ such that the intertwiners between the tensor powers of $U$ coincide with the given collection of operators. We then explain how the general version of Woronowicz Tannaka-Krein duality can be deduced from this.</p>Sara Malacarne
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-20122115116010.7146/math.scand.a-97320Issue covers
http://www.mscand.dk/article/view/104332
Issue coversMathematica Scandinavica
Copyright (c) 2018 MATHEMATICA SCANDINAVICA
2018-02-202018-02-201221