• Can. Math. Bull. (IF 0.655) Pub Date : 2020-12-28
Hans Franzen; Markus Reineke; Silvia Sabatini

We exhibit a large class of quiver moduli spaces, which are Fano varieties, by studying line bundles on quiver moduli and their global sections in general, and work out several classes of examples, comprising moduli spaces of point configurations, Kronecker moduli, and toric quiver moduli.

更新日期：2021-01-19
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-12-28
James Lewis; Jenan Shtayat

We introduce a weak Lefschetz-type result on Chow groups of complete intersections. As an application, we can reproduce some of the results in [P]. The purpose of this paper is not to reproduce all of [P] but rather illustrate why the aforementioned weak Lefschetz result is an interesting idea worth exploiting in itself. We hope the reader agrees.

更新日期：2021-01-12
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-12-07
Raffaele Scandone; Lorenzo Luperi Baglini; Kyrylo Simonov

We study a class of delta-like perturbations of the Laplacian on the half-line, characterized by Robin boundary conditions at the origin. Using the formalism of nonstandard analysis, we derive a simple connection with a suitable family of Schrödinger operators with potentials of very large (infinite) magnitude and very short (infinitesimal) range. As a consequence, we also derive a similar result for

更新日期：2021-01-12
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-11-26
Daniel Ballesteros-Chávez; Wilhelm Klingenberg; Ben Lambert

We prove the existence of compact spacelike hypersurfaces with prescribed k-curvature in de Sitter space, where the prescription function depends on both space and the tilt function.

更新日期：2021-01-08
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-12-02
Thomas Ransford

It is known that if $S(z)$ is a non-constant singular inner function defined on the unit disk, then $\min _{|z|\le r}|S(z)|\to 0$ as $r\to 1^-$. We show that the convergence can be arbitrarily slow.

更新日期：2020-12-18
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-12-02
Matteo Bordignon

In this paper, we obtain a variation of the Pólya–Vinogradov inequality with the sum restricted to a certain height. Assume $\chi$ to be a primitive character modulo q, $\epsilon>0$ and $N\le q^{1-\gamma }$, with $0\le \gamma \le 1/3$. We prove that \begin{align*} |\sum_{n=1}^N \chi(n) |\le c (\tfrac{1}{3} -\gamma+\epsilon )\sqrt{q}\log q \end{align*}with $c=2/\pi ^2$ if $\chi$ is even and

更新日期：2020-12-18
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-11-23
Fernando Szechtman

We answer a question posed by Mordell in 1953, in the case of repeated radical extensions, and find necessary and sufficient conditions for $[F[\sqrt [m_1]{N_1},\dots ,\sqrt [m_\ell ]{N_\ell }]:F]=m_1\cdots m_\ell$, where F is an arbitrary field of characteristic not dividing any $m_i$.

更新日期：2020-12-18
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-11-13
Patrick Ingram

We demonstrate how recent work of Favre and Gauthier, together with a modification of a result of the author, shows that a family of polynomials with infinitely many post-critically finite specializations cannot have any periodic cycles with multiplier of very low degree, except those that vanish, generalizing results of Baker and DeMarco, and Favre and Gauthier.

更新日期：2020-12-18
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-28
Francesco Cellarosi

We consider autocorrelation functions for supersymmetric quantum mechanical systems (consisting of a fermion and a boson) confined in trigonometric Pöschl–Teller partner potentials. We study the limit of rescaled autocorrelation functions (at random time) as the localization of the initial state goes to infinity. The limiting distribution can be described using pairs of Jacobi theta functions on a

更新日期：2020-12-18
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-22
Nguyen Tuan Duy; Nguyen Lam; Phi Long Le

We set up the sharp Trudinger–Moser inequality under arbitrary norms. Using this result and the $L_{p}$ Busemann-Petty centroid inequality, we will provide a new proof to the sharp affine Trudinger–Moser inequalities without using the well-known affine Pólya–Szegö inequality.

更新日期：2020-12-18
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-30

Let G be a locally compact group and let $\omega$ be a continuous weight on G. In this paper, we first characterize bicontinuous biseparating algebra isomorphisms between weighted $L^p$ -algebras. As a result, we extend previous results of Edwards, Parrott, and Strichartz on algebra isomorphisms between $L^p$ -algebras to the setting of weighted $L^p$ -algebras. We then study the automorphisms of

更新日期：2020-11-23
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-28
A. F. Beardon; D. Minda

Many authors define an isometry of a metric space to be a distance-preserving map of the space onto itself. In this note, we discuss spaces for which surjectivity is a consequence of the distance-preserving property rather than an initial assumption. These spaces include, for example, the three classical (Euclidean, spherical, and hyperbolic) geometries of constant curvature that are usually discussed

更新日期：2020-11-21
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-28
Yin Chen

We exhibit a set of generating relations for the modular invariant ring of a vector and a covector for the two-dimensional general linear group over a finite field.

更新日期：2020-11-13
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-11-05
Lucile Devin

As pointed out by Alexandre Bailleul, the paper mentioned in the title contains a mistake in Theorem 2.2. The hypothesis on the linear relation of the almost periods is not sufficient. In this note, we fix the problem and its minor consequences on other results in the same paper.

更新日期：2020-11-06
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-13
Xiang He

We show that the space $G^r_{\underline d}(X)$ of linear series of certain multi-degree $\underline d=(d_1,d_2)$ (including the balanced ones) and rank r on a general genus-g binary curve X has dimension $\rho _{g,r,d}=g-(r+1)(g-d+r)$ if nonempty, where $d=d_1+d_2$ . This generalizes Caporaso’s result from the case $r\leq 2$ to arbitrary rank, and shows that the space of Osserman-limit linear series

更新日期：2020-11-06
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-08
Rolando Perez

We prove that if f and g are holomorphic functions on an open connected domain, with the same moduli on two intersecting segments, then $f=g$ up to the multiplication of a unimodular constant, provided the segments make an angle that is an irrational multiple of $\pi$ . We also prove that if f and g are functions in the Nevanlinna class, and if $|f|=|g|$ on the unit circle and on a circle inside the

更新日期：2020-11-03
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-11
Daniel López Garcia

In this note, we study homology classes in the mirror quintic Calabi–Yau threefold that can be realized by special Lagrangian submanifolds. We have used Picard–Lefschetz theory to establish the monodromy action and to study the orbit of Lagrangian vanishing cycles. For many prime numbers $p,$ we can compute the orbit modulo p. We conjecture that the orbit in homology with coefficients in $\mathbb {Z}$

更新日期：2020-11-03
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-10-15
Andrea Lucchini

We consider the graph $\Gamma _{\text {virt}}(G)$ whose vertices are the elements of a finitely generated profinite group G and where two vertices x and y are adjacent if and only if they topologically generate an open subgroup of G. We investigate the connectivity of the graph $\Delta _{\text {virt}}(G)$ obtained from $\Gamma _{\text {virt}}(G)$ by removing its isolated vertices. In particular, we

更新日期：2020-10-30
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-02
Colin Ingalls; Bruce W. Jordan; Allan Keeton; Adam Logan; Yevgeny Zaytman

For an integer $n\geq 8$ divisible by $4$ , let $R_n={\mathbb Z}[\zeta _n,1/2]$ and let $\operatorname {\mathrm {U_{2}}}(R_n)$ be the group of $2\times 2$ unitary matrices with entries in $R_n$ . Set $\operatorname {\mathrm {U_2^\zeta }}(R_n)=\{\gamma \in \operatorname {\mathrm {U_{2}}}(R_n)\mid \det \gamma \in \langle \zeta _n\rangle \}$ . Let $\mathcal {G}_n\subseteq \operatorname {\mathrm {U_2^\zeta 更新日期：2020-10-30 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-27 Vu The Khoi; Masakazu Teragaito; Anh T. Tran A slope r is called a left orderable slope of a knot$K \subset S^3$if the 3-manifold obtained by r-surgery along K has left orderable fundamental group. Consider double twist knots$C(2m, \pm 2n)$and$C(2m+1, -2n)$in the Conway notation, where$m \ge 1$and$n \ge 2$are integers. By using continuous families of hyperbolic${\mathrm {SL}}_2(\mathbb {R})$-representations of knot groups, it was 更新日期：2020-10-30 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-21 Rhea Palak Bakshi; Dionne Ibarra; Gabriel Montoya-Vega; Józef H. Przytycki; Deborah Weeks We show that the only way of changing the framing of a link by ambient isotopy in an oriented$3$-manifold is when the manifold has a properly embedded non-separating$S^{2}$. This change of framing is given by the Dirac trick, also known as the light bulb trick. The main tool we use is based on McCullough’s work on the mapping class groups of$3$-manifolds. We also relate our results to the theory 更新日期：2020-10-19 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-07 Fatemeh Abtahi Let$\mathcal A$and$\mathcal B$be commutative and semisimple Banach algebras and let$\theta \in \Delta (\mathcal B)$. In this paper, we prove that$\mathcal A\times _{\theta }\mathcal B$is a type I-BSE algebra if and only if${\mathcal A}_e$and$\mathcal B$are so. As a main application of this result, we prove that$\mathcal A\times _{\theta }\mathcal B$is isomorphic with a$C^*$-algebra 更新日期：2020-10-17 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-04 Tran-Trung Nghiem; Zinovy Reichstein Let k be a field,$x_1, \dots , x_n$be independent variables and let$L_n = k(x_1, \dots , x_n)$. The symmetric group$\operatorname {\Sigma }_n$acts on$L_n$by permuting the variables, and the projective linear group$\operatorname {PGL}_2acts by \begin{align*} \begin{pmatrix} a & b \\ c & d \end{pmatrix}\, \colon x_i \longmapsto \frac{a x_i + b}{c x_i + d} \end{align*} for eachi = 1

更新日期：2020-10-17
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-07
Helen W. J. Zhang

In this paper, we decompose $\overline {D}(a,M)$ into modular and mock modular parts, so that it gives as a straightforward consequencethe celebrated results of Bringmann and Lovejoy on Maass forms. Let $\overline {p}(n)$ be the number of partitions of n and $\overline {N}(a,M,n)$ be the number of overpartitions of n with rank congruent to a modulo M. Motivated by Hickerson and Mortenson, we find and

更新日期：2020-10-13
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-24
Damir Kinzebulatov

We consider Kolmorogov operator $-\Delta +b \cdot \nabla$ with drift b in the class of form-bounded vector fields (containing vector fields having critical-order singularities). We characterize quantitative dependence of the Sobolev and Hölder regularity of solutions to the corresponding elliptic equation on the value of the form-bound of b.

更新日期：2020-10-12
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-14
Robert M. Anderson; Haosui Duanmu; Aaron Smith

Yuval Peres and Perla Sousi showed that the mixing times and average mixing times of reversible Markov chains on finite state spaces are equal up to some universal multiplicative constant. We use tools from nonstandard analysis to extend this result to reversible Markov chains on compact state spaces that satisfy the strong Feller property.

更新日期：2020-10-12
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-29
Tao Lei

We study the scaling limit of a random forest with prescribed degree sequence in the regime that the largest tree consists of all but a vanishing fraction of nodes. We give a description of the limit of the forest consisting of the small trees, by relating a plane forest to a marked cyclic forest and its corresponding skip-free walk.

更新日期：2020-10-11
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-02
J. Khodabandehlou; S. Maghsoudi; J. B. Seoane-Sepúlveda

This work focuses on the ongoing research of lineability (the search for large linear structures within certain non-linear sets) in non-Archimedean frameworks. Among several other results, we show that there exist large linear structures inside each of the following sets: (i) functions with a fixed closed subset of continuity, (ii) all continuous functions that are not Darboux continuous (or vice versa)

更新日期：2020-10-11
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-03
Anton A. Klyachko

According to Mazhuga’s theorem, the fundamental group H of anyconnected surface, possibly except for the Klein bottle, is a retract of each finitely generated group containing H as a verbally closed subgroup. We prove that the Klein bottle group is indeed an exception but has a very close property.

更新日期：2020-10-08
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-20
William Chan

A set $U \subseteq {\mathbb {R}} \times {\mathbb {R}}$ is universal for countable subsets of ${\mathbb {R}}$ if and only if for all $x \in {\mathbb {R}}$ , the section $U_x = \{y \in {\mathbb {R}} : U(x,y)\}$ is countable and for all countable sets $A \subseteq {\mathbb {R}}$ , there is an $x \in {\mathbb {R}}$ so that $U_x = A$ . Define the equivalence relation $E_U$ on ${\mathbb {R}}$ by $x_0 \ E_U 更新日期：2020-10-05 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-20 Shubham Dwivedi We prove some results for the solitons of the Ricci–Bourguignon flow, generalizing the corresponding results for Ricci solitons. Taking motivation from Ricci almost solitons, we then introduce the notion of Ricci–Bourguignon almost solitons and prove some results about them that generalize previous results for Ricci almost solitons. We also derive integral formulas for compact gradient Ricci–Bourguignon 更新日期：2020-10-05 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-20 Rajendra Bhatia; Tanvi Jain If A is a real$2n \times 2n$positive definite matrix, then there exists a symplectic matrix M such that$M^TAM=\text {diag}(D, D),$where D is a positive diagonal matrix with diagonal entries$d_1(A)\leqslant \cdots \leqslant d_n(A).$We prove a maxmin principle for$d_k(A)$akin to the classical Courant–Fisher–Weyl principle for Hermitian eigenvalues and use it to derive an analogue of the Weyl 更新日期：2020-10-05 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-20 Jean-Philippe Burelle We show local rigidity of hyperbolic triangle groups generated by reflections in pairs of n-dimensional subspaces of$\mathbb {R}^{2n}$obtained by composition of the geometric representation in$\mathsf {PGL}(2,\mathbb {R})$with the diagonal embeddings into$\mathsf {PGL}(2n,\mathbb {R})$and$\mathsf {PSp}^\pm (2n,\mathbb {R})$. 更新日期：2020-10-02 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-06 Sam Vandervelde By taking square lattices as a two-dimensional analogue to Beatty sequences, we are motivated to define and explore the notion of complementary lattices. In particular, we present a continuous one-parameter family of complementary lattices. This main result then yields several novel examples of complementary sequences, along with a geometric proof of the fundamental property of Beatty sequences. 更新日期：2020-09-28 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-14 Ehud de Shalit Let P and Q be relatively prime integers greater than 1, and let f be a real valued discretely supported function on a finite dimensional real vector space V. We prove that if$f_{P}(x)=f(Px)-f(x)$and$f_{Q}(x)=f(Qx)-f(x)$are both$\Lambda $-periodic for some lattice$\Lambda \subset V$, then so is f (up to a modification at$0$). This result is used to prove a theorem on the arithmetic of elliptic 更新日期：2020-09-23 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-17 Jorge Mello We study intersections of orbits in polynomial semigroup dynamics with lines on the affine plane over a number field, extending previous work of D. Ghioca, T. Tucker, and M. Zieve (2008). 更新日期：2020-09-23 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-10 Anar Akhmedov; B. Doug Park Building upon our earlier work with M. C. Hughes, we construct many new smooth structures on closed simply connected nonspin$4$-manifolds with positive signature. We also provide numerical and asymptotic upper bounds on the function$\lambda (\sigma )$that was defined in our earlier work. 更新日期：2020-09-18 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-17 Samer Dweik We consider the problem of finding two free export/import sets$E^+$and$E^-$that minimize the total cost of some export/import transportation problem (with export/import taxes$g^\pm $), between two densities$f^+$and$f^-$, plus penalization terms on$E^+$and$E^-$. First, we prove the existence of such optimal sets under some assumptions on$f^\pm $and$g^\pm $. Then we study some properties 更新日期：2020-09-17 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-09-08 Ruishen Qian; Xiangling Zhu In this paper, we study the boundedness and compactness of the inclusion mapping from Dirichlet type spaces$\mathcal {D}^{p}_{p-1 }$to tent spaces. Meanwhile, the boundedness, compactness, and essential norm of Volterra integral operators from Dirichlet type spaces$\mathcal {D}^{p}_{p-1 }$to general function spaces are also investigated. 更新日期：2020-09-08 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-08 John Kopper We compute the nef cone of the Hilbert scheme of points on a general rational elliptic surface. As a consequence of our computation, we show that the Morrison–Kawamata cone conjecture holds for these nef cones. 更新日期：2020-08-14 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-08-13 Alberto Debernardi; Elijah Liflyand Truncating the Fourier transform averaged by means of a generalized Hausdorff operator, we approximate functions and the adjoint to that Hausdorff operator of the given function. We find estimates for the rate of approximation in various metrics in terms of the parameter of truncation and the components of the Hausdorff operator. Explicit rates of approximation of functions and comparison with approximate 更新日期：2020-08-13 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-08 Paul Pollack For each positive integer n, let$U(\mathbf {Z}/n\mathbf {Z})$denote the group of units modulo n, which has order$\phi (n)$(Euler’s function) and exponent$\lambda (n)$(Carmichael’s function). The ratio$\phi (n)/\lambda (n)$is always an integer, and a prime p divides this ratio precisely when the (unique) Sylow p-subgroup of$U(\mathbf {Z}/n\mathbf {Z})$is noncyclic. Write W(n) for the number 更新日期：2020-08-11 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-29 Sheng Bau; Peter Johnson; Matt Noble For positive integers n and d > 0, let$G(\mathbb {Q}^n,\; d)$denote the graph whose vertices are the set of rational points$\mathbb {Q}^n$, with$u,v \in \mathbb {Q}^n$being adjacent if and only if the Euclidean distance between u and v is equal to d. Such a graph is deemed “non-trivial” if d is actually realized as a distance between points of$\mathbb {Q}^n$. In this paper, we show that a space 更新日期：2020-07-29 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-27 Clément Coine In this paper, we characterize the multiple operator integrals mappings that are bounded on the Haagerup tensor product of spaces of compact operators. We show that such maps are automatically completely bounded and prove that this is equivalent to a certain factorization property of the symbol associated with the operator integral mapping. This generalizes a result by Juschenko-Todorov-Turowska on 更新日期：2020-07-27 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-22 Gregorio Baldi; Giada Grossi Let S be a finite set of primes. We prove that a form of finite Galois descent obstruction is the only obstruction to the existence of$\mathbb {Z}_{S}$-points on integral models of Hilbert modular varieties, extending a result of D. Helm and F. Voloch about modular curves. Let L be a totally real field. Under (a special case of) the absolute Hodge conjecture and a weak Serre’s conjecture for mod 更新日期：2020-07-22 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-15 Jan J. Dijkstra; David S. Lipham We investigate C-sets in almost zero-dimensional spaces, showing that closed$\sigma $C-sets are C-sets. As corollaries, we prove that every rim-$\sigma $-compact almost zero-dimensional space is zero-dimensional and that each cohesive almost zero-dimensional space is nowhere rational. To show that these results are sharp, we construct a rim-discrete connected set with an explosion point. We also 更新日期：2020-07-15 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-10 Naoki Endo; Shiro Goto; Ryotaro Isobe The purpose of this paper is, as part of the stratification of Cohen–Macaulay rings, to investigate the question of when the fiber products are almost Gorenstein rings. We show that the fiber product$R \times _T S$of Cohen–Macaulay local rings R, S of the same dimension$d>0$over a regular local ring T with$\dim T=d-1$is an almost Gorenstein ring if and only if so are R and S. In addition, the 更新日期：2020-07-10 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-10 Andrew Bridy; John R. Doyle; Dragos Ghioca; Liang-Chung Hsia; Thomas J. Tucker We formulate a general question regarding the size of the iterated Galois groups associated with an algebraic dynamical system and then we discuss some special cases of our question. Our main result answers this question for certain split polynomial maps whose coordinates are unicritical polynomials. 更新日期：2020-07-10 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-07-01 Itay Griniasty; Ruth Lawrence We give explicit formulae for differential graded Lie algebra (DGLA) models of 3-cells. In particular, for a cube and an n-faceted banana-shaped 3-cell with two vertices, n edges each joining those two vertices, and n bi-gon 2-cells, we construct a model symmetric under the geometric symmetries of the cell fixing two antipodal vertices. The cube model is to be used in forthcoming work for discrete 更新日期：2020-07-01 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-29 Stamatis Pouliasis We show that condenser capacity varies continuously under holomorphic motions, and the corresponding family of the equilibrium measures of the condensers is continuous with respect to the weak-star convergence. We also study the behavior of uniformly perfect sets under holomorphic motions. 更新日期：2020-06-29 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-29 Haining Wang Using the axioms of He and Rapoport for the stratifications of Shimura varieties, we explain a result of Görtz, He, and Nie that the EKOR strata contained in the basic loci can be described as a disjoint union of Deligne–Lusztig varieties. In the special case of Siegel modular varieties, we compare their descriptions to that of Görtz and Yu for the supersingular Kottwitz-Rapoport strata and to the 更新日期：2020-06-29 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-22 Gene Abrams; Francesca Mantese; Alberto Tonolo For a field K, let$\mathcal {R}$denote the Jacobson algebra$K\langle X, Y \ | \ XY=1\rangle $. We give an explicit construction of the injective envelope of each of the (infinitely many) simple left$\mathcal {R}$-modules. Consequently, we obtain an explicit description of a minimal injective cogenerator for$\mathcal {R}$. Our approach involves realizing$\mathcal {R}$up to isomorphism as the 更新日期：2020-06-22 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-22 Amaury Freslon We consider the sequence of powers of a positive definite function on a discrete group. Taking inspiration from random walks on compact quantum groups, we give several examples of situations where a cut-off phenomenon occurs for this sequence, including free groups and infinite Coxeter groups. We also give examples of absence of cut-off using free groups again. 更新日期：2020-06-22 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-16 Jens Harlander; Stephan Rosebrock Diagrammatic reducibility DR and its generalization, vertex asphericity VA, are combinatorial tools developed for detecting asphericity of a 2-complex. Here we present tests for a relative version of VA that apply to pairs of 2-complexes$(L,K)$, where K is a subcomplex of L. We show that a relative weight test holds for injective labeled oriented trees, implying that they are VA and hence aspherical 更新日期：2020-06-16 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-15 Alexandros Eskenazis We prove an extension of Pisier’s inequality (1986) with a dimension-independent constant for vector-valued functions whose target spaces satisfy a relaxation of the UMD property. 更新日期：2020-06-15 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-11 Tongmu He Let K be a complete discrete valuation field of characteristic$0$, with not necessarily perfect residue field of characteristic$p>0$. We define a Faltings extension of$\mathcal {O}_K$over$\mathbb {Z}_p$, and we construct a Hodge-Tate filtration for abelian varieties over K by generalizing Fontaine’s construction [Fon82] where he treated the perfect residue field case. 更新日期：2020-06-11 • Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-11 Augustin Mouze; Vincent Munnier For any$\alpha \in \mathbb {R},$we consider the weighted Taylor shift operators$T_{\alpha }$acting on the space of analytic functions in the unit disc given by$T_{\alpha }:H(\mathbb {D})\rightarrow H(\mathbb {D}), \begin{align*}f(z)=\sum_{k\geq 0}a_{k}z^{k}\mapsto T_{\alpha}(f)(z)=a_1+\sum_{k\geq 1}\Big(1+\frac{1}{k}\Big)^{\alpha}a_{k+1}z^{k}.\end{align*}\$ We establish the optimal growth of

更新日期：2020-06-11
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-06-11
Anwesh Ray; R. Sujatha

The notion of the truncated Euler characteristic for Iwasawa modules is an extension of the notion of the usual Euler characteristic to the case when the homology groups are not finite. This article explores congruence relations between the truncated Euler characteristics for dual Selmer groups of elliptic curves with isomorphic residual representations, over admissible p-adic Lie extensions. Our results

更新日期：2020-06-11
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-05-15
Min Sha; Igor E. Shparlinski

Recently E. Bombieri and N. M. Katz (2010) demonstrated that several well-known results about the distribution of values of linear recurrence sequences lead to interesting statements for Frobenius traces of algebraic curves. Here we continue this line of study and establish the Möbius randomness law quantitatively for the normalised form of Frobenius traces.

更新日期：2020-05-15
• Can. Math. Bull. (IF 0.655) Pub Date : 2020-05-12
Zhao Yang; Xiaoling Zhang

In this paper, we study Finsler warped product metrics with relatively isotropic Landsberg curvature. We obtain the differential equations that characterize such metrics. Then we give some examples.

更新日期：2020-05-12
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