
« 2013 (v56)  2015 (v58) » 
Page 


3  A Short Proof of Paouris' Inequality Adamczak, Radosław; Latała, Rafał; Litvak, Alexander E.; Oleszkiewicz, Krzysztof; Pajor, Alain; TomczakJaegermann, Nicole
We give a short proof of a result of G.~Paouris on
the tail behaviour of the Euclidean norm $X$ of an isotropic
logconcave random vector $X\in\mathbb{R}^n,$
stating that for every $t\geq 1$,
\[\mathbb{P} \big( X\geq ct\sqrt n\big)\leq \exp(t\sqrt n).\]
More precisely we show that for any logconcave random vector $X$
and any $p\geq 1$,
\[(\mathbb{E}X^p)^{1/p}\sim \mathbb{E} X+\sup_{z\in
S^{n1}}(\mathbb{E} \langle
z,X\rangle^p)^{1/p}.\]


9  Integral Sets and the Center of a Finite Group Alperin, Roger C.; Peterson, Brian L.
We give a description of the atoms in the Boolean algebra generated by the integral subsets of a finite group.


12  On the Continuity of the Eigenvalues of a Sublaplacian Aribi, Amine; Dragomir, Sorin; El Soufi, Ahmad
We study the behavior of the eigenvalues of a sublaplacian $\Delta_b$ on a compact strictly pseudoconvex CR manifold $M$, as functions on the set
${\mathcal P}_+$ of positively oriented contact forms on $M$ by endowing ${\mathcal P}_+$ with a natural metric topology.


25  Subadditivity Inequalities for Compact Operators Bourin, JeanChristophe; Harada, Tetsuo; Lee, EunYoung
Some subadditivity inequalities for matrices and concave functions also hold for Hilbert space operators, but (unfortunately!) with an additional $\varepsilon$ term. It seems not possible to erase this residual term. However, in case of compact operators we show that the $\varepsilon$ term is unnecessary. Further, these inequalities are strict in a certain sense when some natural assumptions are satisfied. The discussion also stresses on matrices and their compressions and several open questions or conjectures are considered, both in the matrix and operator settings.


37  Character Amenability of Lipschitz Algebras Dashti, Mahshid; NasrIsfahani, Rasoul; Renani, Sima Soltani
Let ${\mathcal X}$ be a locally compact metric space and let
${\mathcal A}$ be any of the Lipschitz algebras
${\operatorname{Lip}_{\alpha}{\mathcal X}}$, ${\operatorname{lip}_{\alpha}{\mathcal X}}$ or
${\operatorname{lip}_{\alpha}^0{\mathcal X}}$. In this paper, we show, as a
consequence of rather more general results on Banach algebras,
that ${\mathcal A}$ is $C$character amenable if and only if
${\mathcal X}$ is uniformly discrete.


42  Covering the Unit Sphere of Certain Banach Spaces by Sequences of Slices and Balls Fonf, Vladimir P.; Zanco, Clemente
e prove that, given any covering of any infinitedimensional Hilbert space $H$ by countably many closed balls, some point exists in $H$ which belongs to infinitely many balls. We do that by characterizing isomorphically polyhedral separable Banach spaces as those whose unit sphere admits a pointfinite covering by the union of countably many slices of the unit ball.


51  Jordan $*$Derivations of FiniteDimensional Semiprime Algebras Fošner, Ajda; Lee, TsiuKwen
In the paper, we characterize Jordan $*$derivations of a $2$torsion
free, finitedimensional semiprime algebra $R$ with involution $*$. To
be precise, we prove the theorem: Let $deltacolon R o R$ be a Jordan
$*$derivation. Then there exists a $*$algebra decomposition
$R=Uoplus V$ such that both $U$ and $V$ are invariant under
$delta$. Moreover, $*$ is the identity map of $U$ and $delta,_U$ is a
derivation, and the Jordan $*$derivation $delta,_V$ is inner.
We also prove the theorem: Let $R$ be a noncommutative, centrally
closed prime algebra with involution $*$, $operatorname{char},R
e 2$,
and let $delta$ be a nonzero Jordan $*$derivation of $R$. If $delta$ is
an elementary operator of $R$, then $operatorname{dim}_CRlt infty$ and
$delta$ is inner.


61  2dimensional Convexity Numbers and $P_4$free Graphs Geschke, Stefan
For $S\subseteq\mathbb R^n$ a set
$C\subseteq S$ is an $m$clique if the convex hull of no $m$element subset of
$C$ is contained in $S$.
We show that there is essentially just one way to construct
a closed set $S\subseteq\mathbb R^2$ without an uncountable
$3$clique that is not the union of countably many convex sets.
In particular, all such sets have the same convexity number;
that is, they
require the same number of convex subsets to cover them.
The main result follows from an analysis of the convex structure of closed
sets in $\mathbb R^2$ without uncountable 3cliques in terms of
clopen, $P_4$free graphs on Polish spaces.


72  Un Anneau Commutatif associé à un design symétrique Grari, A.
Dans les articles \cite{1}, \cite{2} et \cite{3}; l'auteur développe une représentation
d'un plan projectif fini par un
anneau commutatif unitaire dont les propriétés algébriques dépendent
de la structure géométrique du plan. Dans l'article \cite{4}; il étend cette représentation aux designs symétriques. Cependant l'auteur de l'article \cite{7} fait remarquer que la multiplication définie dans ce cas ne peut être associative que si le design est un plan projectif.
Dans ce papier on mènera
une étude de cette représentation dans le cas des designs
symétriques. On y montrera comment on peut faire associer un
anneau commutatif unitaire à
tout design symétrique , on y précisera certaines de ses propriétés, en
particulier, celles qui relèvent de son invariance. On caractérisera aussi les géométries projectives finies de dimension supérieure moyennant cette représentation.


80  Semicrossed Products of the Disk Algebra and the Jacobson Radical Khemphet, Anchalee; Peters, Justin R.
We consider semicrossed products of the disk algebra with respect to
endomorphisms defined by finite Blaschke products. We characterize the Jacobson radical
of these operator algebras. Furthermore, in the case the finite Blaschke product is elliptic,
we show that the semicrossed product contains no nonzero quasinilpotent
elements. However, if the finite Blaschke product is hyperbolic or parabolic with positive hyperbolic step,
the Jacobson radical is nonzero and a proper subset of the set of quasinilpotent elements.


90  Compact Subsets of the Glimm Space of a $C^*$algebra Lazar, Aldo J.
If $A$ is a $\sigma$unital $C^*$algebra and $a$ is a strictly positive element of $A$ then for every compact subset $K$ of the complete
regularization $\mathrm{Glimm}(A)$ of $\mathrm{Prim}(A)$ there exists
$\alpha \gt 0$ such that $K\subset \{G\in \mathrm{Glimm}(A) \mid \Vert a + G\Vert \geq
\alpha\}$. This extends
a result of J. Dauns
to all $\sigma$unital $C^*$algebras. However, there are a $C^*$algebra $A$
and a compact subset of $\mathrm{Glimm}(A)$ that is not contained in any set of the form $\{G\in \mathrm{Glimm}(A) \mid \Vert a + G\Vert \geq
\alpha\}$, $a\in A$ and $\alpha \gt 0$.


97  Rationality and the JordanGattiViniberghi decomposition Levy, Jason
We verify
our earlier conjecture
and use it to prove that the
semisimple parts of the rational JordanKacVinberg decompositions of
a rational vector all lie in a single rational orbit.


105  On the Counting Function of Elliptic Carmichael Numbers Luca, Florian; Shparlinski, Igor E.
We give an upper bound for the number elliptic Carmichael numbers $n \le x$
that have recently been introduced by J. H. Silverman in the case of an elliptic curve without complex multiplication (non CM). We also discuss
several possible ways for further improvements.


113  A Lower Bound for the EndtoEnd Distance of SelfAvoiding Walk Madras, Neal
For an $N$step selfavoiding walk on the hypercubic lattice ${\bf Z}^d$,
we prove that the meansquare endtoend distance is at least
$N^{4/(3d)}$ times a constant.
This implies that the associated critical exponent $\nu$ is
at least $2/(3d)$, assuming that $\nu$ exists.


119  Splitting Families and Complete Separability Mildenberger, Heike; Raghavan, Dilip; Steprans, Juris
We answer a question from Raghavan and Steprāns
by showing that $\mathfrak{s} = {\mathfrak{s}}_{\omega, \omega}$. Then we use this to construct a completely separable maximal almost disjoint family under $\mathfrak{s} \leq \mathfrak{a}$, partially answering a question of Shelah.


125  Camina Triples Mlaiki, Nabil M.
In this paper, we study Camina triples. Camina triples are a
generalization of Camina pairs. Camina pairs were first introduced
in 1978 by A .R. Camina.
Camina's work
was inspired by the study of Frobenius groups. We
show that if $(G,N,M)$ is a Camina triple, then either $G/N$ is a
$p$group, or $M$ is abelian, or $M$ has a nontrivial nilpotent or
Frobenius quotient.


132  Twisted Conjugacy Classes in Abelian Extensions of Certain Linear Groups Mubeena, T.; Sankaran, P.
Given a group automorphism $\phi:\Gamma\longrightarrow \Gamma$, one has
an action of $\Gamma$ on itself by $\phi$twisted conjugacy, namely, $g.x=gx\phi(g^{1})$.
The orbits of this action are called $\phi$twisted conjugacy classes. One says
that $\Gamma$ has the $R_\infty$property if there are infinitely many $\phi$twisted conjugacy
classes for every automorphism $\phi$ of $\Gamma$. In this paper we
show that $\operatorname{SL}(n,\mathbb{Z})$ and its
congruence subgroups have the $R_\infty$property. Further we show that
any (countable) abelian extension of $\Gamma$ has the $R_\infty$property where $\Gamma$ is a torsion
free nonelementary hyperbolic group, or $\operatorname{SL}(n,\mathbb{Z}),
\operatorname{Sp}(2n,\mathbb{Z})$ or a principal congruence
subgroup of $\operatorname{SL}(n,\mathbb{Z})$ or the fundamental group of a complete Riemannian
manifold of constant negative curvature.


141  Size, Order, and Connected Domination Mukwembi, Simon
We give a sharp upper bound on the size of a
trianglefree graph of a given order and connected domination. Our
bound, apart from
strengthening an old classical theorem of Mantel and of
Turán , improves on a theorem of Sanchis.
Further, as corollaries, we settle a long standing
conjecture of Graffiti on the leaf number and local independence for
trianglefree graphs and answer a question of Griggs, Kleitman and
Shastri on a lower bound of the leaf number in
trianglefree graphs.


145  The Essential Spectrum of the Essentially Isometric Operator Mustafayev, H. S.
Let $T$ be a contraction on a complex, separable, infinite dimensional
Hilbert space and let $\sigma \left( T\right) $ (resp. $\sigma _{e}\left(
T\right) )$ be its spectrum (resp. essential spectrum). We assume that $T$
is an essentially isometric operator, that is $I_{H}T^{\ast }T$ is compact.
We show that if $D\diagdown \sigma \left( T\right) \neq \emptyset ,$ then
for every $f$ from the discalgebra,
\begin{equation*}
\sigma _{e}\left( f\left( T\right) \right) =f\left( \sigma _{e}\left(
T\right) \right) ,
\end{equation*}
where $D$ is the open unit disc. In addition, if $T$ lies in the class
$ C_{0\cdot }\cup C_{\cdot 0},$ then
\begin{equation*}
\sigma _{e}\left( f\left( T\right) \right) =f\left( \sigma \left( T\right)
\cap \Gamma \right) ,
\end{equation*}
where $\Gamma $ is the unit circle. Some related problems are also discussed.


159  Strongly $0$dimensional Modules Oral, Kürşat Hakan; Özkirişci, Neslihan Ayşen; Tekir, Ünsal
In a multiplication module, prime submodules have the property, if a prime
submodule contains a finite intersection of submodules then one of the
submodules is contained in the prime submodule. In this paper, we generalize
this property to infinite intersection of submodules and call such prime
submodules strongly prime submodule. A multiplication module in which every
prime submodule is strongly prime will be called strongly 0dimensional
module. It is also an extension of strongly 0dimensional rings. After
this we investigate properties of strongly 0dimensional modules and give
relations of von Neumann regular modules, Qmodules and strongly
0dimensional modules.


166  On Minimal and Maximal $p$operator Space Structures Öztop, Serap; Spronk, Nico
We show that for $p$operator spaces, there are natural notions of minimal and maximal
structures. These are useful for dealing with tensor products.


178  Quasiconvexity and Density Topology Rabier, Patrick J.
We prove that if $f:\mathbb{R}^{N}\rightarrow \overline{\mathbb{R}}$ is
quasiconvex and $U\subset \mathbb{R}^{N}$ is open in the density topology, then
$\sup_{U}f=\operatorname{ess\,sup}_{U}f,$ while
$\inf_{U}f=\operatorname{ess\,inf}_{U}f$
if and only if the equality holds when $U=\mathbb{R}^{N}.$ The first (second)
property is typical of lsc (usc) functions and, even when $U$ is an ordinary
open subset, there seems to be no record that they both hold for all
quasiconvex functions.


188  A Characterization of Bipartite Zerodivisor Graphs Rad, Nader Jafari; Jafari, Sayyed Heidar
In this paper we obtain a characterization for all bipartite
zerodivisor graphs of commutative rings $R$ with $1$, such that
$R$ is finite or $Nil(R)\neq2$.


194  A Lower Bound for the Length of Closed Geodesics on a Finsler Manifold Zhao, Wei
In this paper, we obtain a lower bound for the length of closed geodesics on an arbitrary closed Finsler manifold.


209  Erratum to the Paper "A Lower Bound for the Length of Closed Geodesics on a Finsler Manifold" Zhao, Wei
We correct two clerical errors made in the paper "A Lower Bound for
the Length of Closed Geodesics on a Finsler Manifold".


210  An Explicit Formula for the Generalized Cyclic Shuffle Map Zhang, Jiao; Wang, QingWen
We provide an explicit formula for the generalized cyclic shuffle map for cylindrical modules.
Using this formula we give a combinatorial proof of the generalized
cyclic EilenbergZilber theorem.


225  Small Flag Complexes with Torsion Adamaszek, Michał
We classify flag complexes on at most $12$ vertices with torsion in
the first homology group. The result is moderately computeraided.


231  On the Multiplicities of Characters in Table Algebras Bagherian, J.
In this paper we show that every module of a table algebra
can be considered as a faithful module of some quotient table
algebra.
Also we prove that every faithful module of a table algebra
determines a closed subset which is a cyclic group.
As a main result we give some information about multiplicities
of characters in table algebras.


240  Addendum to ``Limit Sets of Typical Homeomorphisms'' Bernardes, Nilson C. Jr.
Given an integer $n \geq 3$,
a metrizable compact topological $n$manifold $X$ with boundary,
and a finite positive Borel measure $\mu$ on $X$,
we prove that for the typical homeomorphism $f : X \to X$,
it is true that for $\mu$almost every point $x$ in $X$ the restriction of
$f$ (respectively of $f^{1}$) to the omega limit set $\omega(f,x)$
(respectively to the alpha limit set $\alpha(f,x)$) is topologically
conjugate to the universal odometer.


245  AssouadNagata Dimension of Wreath Products of Groups Brodskiy, N.; Dydak, J.; Lang, U.
Consider the wreath product $H\wr G$, where $H\ne 1$ is finite and $G$ is finitely generated.
We show that the AssouadNagata dimension $\dim_{AN}(H\wr G)$ of $H\wr G$
depends on the growth of $G$ as follows:
\par If the growth of $G$ is not bounded by a linear function, then $\dim_{AN}(H\wr G)=\infty$,
otherwise $\dim_{AN}(H\wr G)=\dim_{AN}(G)\leq 1$.


254  On Parseval Wavelet Frames with Two or Three Generators via the Unitary Extension Principle Christensen, Ole; Kim, Hong Oh; Kim, Rae Young
The unitary extension principle (UEP) by Ron and Shen yields a
sufficient condition for the construction of Parseval wavelet frames with
multiple generators. In this paper we characterize the UEPtype wavelet systems that
can be extended to a Parseval wavelet frame by adding just one UEPtype wavelet
system. We derive a condition that is necessary for the extension of a UEPtype
wavelet system to any Parseval wavelet frame with any number of generators, and
prove that this condition is also sufficient to ensure that an extension
with just two generators is possible.


264  On Semisimple Hopf Algebras of Dimension $pq^n$ Dai, Li; Dong, Jingcheng
Let $p,q$ be prime numbers with $p^2\lt q$, $n\in \mathbb{N}$, and $H$ a
semisimple Hopf algebra of dimension $pq^n$ over an algebraically
closed field of characteristic $0$. This paper proves that $H$ must
possess one of the following structures: (1) $H$ is semisolvable;
(2) $H$ is a Radford biproduct $R\# kG$, where $kG$ is the group
algebra of group $G$ of order $p$, and $R$ is a semisimple YetterDrinfeld
Hopf algebra in ${}^{kG}_{kG}\mathcal{YD}$ of dimension $q^n$.


270  Derivations on Toeplitz Algebras Didas, Michael; Eschmeier, Jörg
Let $H^2(\Omega)$ be the Hardy space on a strictly pseudoconvex domain $\Omega \subset
\mathbb{C}^n$,
and let $A \subset L^\infty(\partial \Omega)$ denote the subalgebra of all $L^\infty$functions $f$
with compact Hankel operator $H_f$. Given any closed subalgebra $B \subset A$ containing $C(\partial \Omega)$,
we describe the first Hochschild cohomology group of the
corresponding Toeplitz algebra $\mathcal(B) \subset B(H^2(\Omega))$.
In particular, we show that every derivation on $\mathcal{T}(A)$ is inner. These results are new even for $n=1$,
where it follows that every derivation on $\mathcal{T}(H^\infty+C)$ is inner, while there are noninner
derivations on $\mathcal{T}(H^\infty+C(\partial \mathbb{B}_n))$ over
the unit ball $\mathbb{B}_n$ in dimension $n\gt 1$.


277  On Mutually $m$permutable Product of Smooth Groups Elkholy, A. M.; ElLatif, M. H. Abd
Let $G$ be a
finite group and $H$, $K$ two subgroups of G. A group $G$ is said to
be a mutually mpermutable product of $H$ and $K$ if $G=HK$ and
every maximal subgroup of $H$ permutes with $K$ and every maximal
subgroup of $K$ permutes with $H$. In this paper, we investigate the
structure of a finite group which is a mutually mpermutable product
of two subgroups under the assumption that its maximal subgroups are
totally smooth.


283  Infinite Dimensional DeWitt Supergroups and their Bodies Fulp, Ronald
For Dewitt super groups $G$ modeled via an underlying finitely
generated Grassmann algebra it is wellknown that when there exists a
body group $BG$ compatible with the group operation on $G,$ then
generically the kernel $K$ of the body homomorphism is nilpotent. This
is not true when the underlying Grassmann algebra is infinitely
generated. We show that it is quasinilpotent in the sense that as a
Banach Lie group its Lie algebra $\kappa$ has the property that for
each $a\in \kappa$, $ad_a$ has a zero spectrum. We also show that
the exponential mapping from $\kappa$ to $K$ is surjective and that
$K$ is a quotient manifold of the Banach space $\kappa$ via a lattice
in $\kappa.$


289  Closure of the Cone of Sums of $2d$powers in Certain Weighted $\ell_1$seminorm Topologies Ghasemi, Mehdi; Marshall, Murray; Wagner, Sven
In a paper from 1976, Berg, Christensen and Ressel prove that the
closure of the cone of sums of squares $\sum
\mathbb{R}[\underline{X}]^2$ in the polynomial ring
$\mathbb{R}[\underline{X}] := \mathbb{R}[X_1,\dots,X_n]$ in the
topology induced by the $\ell_1$norm is equal to
$\operatorname{Pos}([1,1]^n)$, the cone consisting of all polynomials
which are nonnegative on the hypercube $[1,1]^n$. The result is
deduced as a corollary of a general result, established in the same
paper, which is valid for any commutative semigroup.
In later work, Berg and Maserick and Berg, Christensen and Ressel
establish an even more general result, for a commutative semigroup
with involution, for the closure of the cone of sums of squares of
symmetric elements in the weighted $\ell_1$seminorm topology
associated to an absolute value.
In the present paper we give a new proof of these results which is
based on Jacobi's representation theorem from 2001. At the same time,
we use Jacobi's representation theorem to extend these results from
sums of squares to sums of $2d$powers, proving, in particular, that
for any integer $d\ge 1$, the closure of the cone of sums of
$2d$powers $\sum \mathbb{R}[\underline{X}]^{2d}$ in
$\mathbb{R}[\underline{X}]$ in the topology induced by the
$\ell_1$norm is equal to $\operatorname{Pos}([1,1]^n)$.


303  Octonion Algebras over Rings are not Determined by their Norms Gille, Philippe
Answering a question of H. Petersson, we provide
a class of examples of pair of octonion algebras over a ring having isometric
norms.


310  Leftorderable Fundamental Group and Dehn Surgery on the Knot $5_2$ Hakamata, Ryoto; Teragaito, Masakazu
We show that the resulting manifold by $r$surgery on the knot $5_2$, which is
the twobridge knot corresponding to the rational number $3/7$, has leftorderable
fundamental group if the slope $r$ satisfies $0\le r \le 4$.


318  Duality of Preenvelopes and Pure Injective Modules Huang, Zhaoyong
Let $R$ be an arbitrary ring and $()^+=\operatorname{Hom}_{\mathbb{Z}}(,
\mathbb{Q}/\mathbb{Z})$ where $\mathbb{Z}$ is the ring of integers
and $\mathbb{Q}$ is the ring of rational numbers, and let
$\mathcal{C}$ be a subcategory of left $R$modules and $\mathcal{D}$
a subcategory of right $R$modules such that $X^+\in \mathcal{D}$
for any $X\in \mathcal{C}$ and all modules in $\mathcal{C}$ are pure
injective. Then a homomorphism $f: A\to C$ of left $R$modules with
$C\in \mathcal{C}$ is a $\mathcal{C}$(pre)envelope of $A$ provided
$f^+: C^+\to A^+$ is a $\mathcal{D}$(pre)cover of $A^+$. Some
applications of this result are given.


326  On Zerodivisors in Group Rings of Groups with Torsion Ivanov, S. V.; Mikhailov, Roman
Nontrivial pairs of zerodivisors in group rings are
introduced and discussed. A problem on the existence of nontrivial
pairs of zerodivisors in group rings of free Burnside groups of odd
exponent $n \gg 1$ is solved in the affirmative. Nontrivial pairs of
zerodivisors are also found in group rings of free products of groups
with torsion.


335  Alexandroff Manifolds and Homogeneous Continua Karassev, A.; Todorov, V.; Valov, V.
ny homogeneous,
metric $ANR$continuum is a $V^n_G$continuum provided $\dim_GX=n\geq
1$ and $\check{H}^n(X;G)\neq 0$, where $G$ is a principal ideal
domain.
This implies that any homogeneous $n$dimensional metric $ANR$continuum is a $V^n$continuum in the sense of Alexandroff.
We also prove that any finitedimensional homogeneous metric continuum
$X$, satisfying $\check{H}^n(X;G)\neq 0$ for some group $G$ and $n\geq
1$, cannot be separated by
a compactum $K$ with $\check{H}^{n1}(K;G)=0$ and $\dim_G K\leq
n1$. This provides a partial answer to a question of
KallipolitiPapasoglu
whether any twodimensional homogeneous Peano continuum cannot be separated by arcs.


344  On Localized Unstable $K^1$groups and Applications to Selfhomotopy Groups Kishimoto, Daisuke; Kono, Akira; Tsutaya, Mitsunobu
The computing method for the $p$localization of the group
$[X,\mathrm{U}(n)]$
by Hamanaka in 2004
is revised. As an application, an explicit description of the
selfhomotopy group of $\mathrm{Sp}(3)$ localized at $p\ge 5$ is given and
the homotopy nilpotency of $\mathrm{Sp}(3)$ localized at $p\ge 5$ is determined.


357  Representation Equivalent Bieberbach Groups and Strongly Isospectral Flat Manifolds Lauret, Emilio A.
Let $\Gamma_1$ and $\Gamma_2$ be Bieberbach groups contained in the
full isometry group $G$ of $\mathbb{R}^n$.
We prove that if the compact flat manifolds $\Gamma_1\backslash\mathbb{R}^n$ and
$\Gamma_2\backslash\mathbb{R}^n$ are strongly isospectral then the Bieberbach groups
$\Gamma_1$ and $\Gamma_2$ are representation equivalent, that is, the
right regular representations $L^2(\Gamma_1\backslash G)$ and
$L^2(\Gamma_2\backslash G)$ are unitarily equivalent.


364  How Lipschitz Functions Characterize the Underlying Metric Spaces Li, Lei; Wang, YaShu
Let $X, Y$ be metric spaces and $E, F$ be Banach spaces. Suppose that
both $X,Y$ are realcompact, or both $E,F$ are realcompact.
The zero set of a vectorvalued function $f$ is denoted by $z(f)$.
A linear bijection $T$ between local or generalized Lipschitz vectorvalued function spaces
is said to preserve zeroset containments or nonvanishing functions
if
\[z(f)\subseteq z(g)\quad\Longleftrightarrow\quad z(Tf)\subseteq z(Tg),\]
or
\[z(f) = \emptyset\quad \Longleftrightarrow\quad z(Tf)=\emptyset,\]
respectively.
Every zeroset containment preserver, and every nonvanishing function preserver when
$\dim E =\dim F\lt +\infty$, is a weighted composition operator
$(Tf)(y)=J_y(f(\tau(y)))$.
We show that the map $\tau\colon Y\to X$ is a locally (little) Lipschitz homeomorphism.


375  A Problem on Edgemagic Labelings of Cycles López, S. C.; MuntanerBatle; RiusFont
Kotzig and Rosa defined in 1970 the concept of edgemagic labelings as
follows: let $G$ be a simple $(p,q)$graph (that is, a graph of order $p$
and size $q$ without loops or multiple edges). A bijective function $f:V(G)\cup
E(G)\rightarrow \{1,2,\ldots,p+q\}$ is an edgemagic labeling of $G$ if
$f(u)+f(uv)+f(v)=k$, for all $uv\in E(G)$. A graph that admits an edgemagic
labeling is called an edgemagic graph, and $k$ is called the magic sum
of the labeling. An old conjecture of Godbold and Slater sets that all
possible theoretical magic sums are attained for each cycle of order $n\ge
7$. Motivated by this conjecture, we prove that for all $n_0\in \mathbb{N}$,
there exists $n\in \mathbb{N}$, such that the cycle $C_n$ admits at least
$n_0$ edgemagic labelings with at least $n_0$ mutually distinct magic
sums. We do this by providing a lower bound for the number of magic sums
of the cycle $C_n$, depending on the sum of the exponents of the odd primes
appearing in the prime factorization of $n$.


381  On Complex Explicit Formulae Connected with the Möbius Function of an Elliptic Curve Łydka, Adrian
We study analytic properties function $m(z, E)$, which is defined on the upper halfplane as an integral from the shifted $L$function of an elliptic curve. We show that $m(z, E)$ analytically continues to a meromorphic function on the whole complex plane and satisfies certain functional equation. Moreover, we give explicit formula for $m(z, E)$ in the strip $\Im{z}\lt 2\pi$.


390  Simplicity of Some Twin Tree Automorphism Groups with Trivial Commutation Relations Morita, Jun; Rémy, Bertrand
We prove simplicity for incomplete rank 2 KacMoody groups over algebraic closures of finite fields with trivial commutation relations between root groups corresponding to prenilpotent pairs.
We don't use the (yet unknown) simplicity of the corresponding finitely generated groups (i.e., when the ground field is finite).
Nevertheless we use the fact that the latter groups are just infinite
(modulo center).


401  Curvature of $K$contact SemiRiemannian Manifolds Perrone, Domenico
In this paper we characterize $K$contact semiRiemannian manifolds
and Sasakian semiRiemannian manifolds in terms of
curvature. Moreover, we show that any conformally flat $K$contact
semiRiemannian manifold is Sasakian and of constant sectional
curvature $\kappa=\varepsilon$, where $\varepsilon =\pm 1$ denotes
the causal character of the Reeb vector field. Finally, we give some
results about the curvature of a $K$contact Lorentzian manifold.


413  On the Comaximal Graph of a Commutative Ring Samei, Karim
Let $R$ be a commutative ring with $1$. In [P. K. Sharma, S. M.
Bhatwadekar, A note on graphical representation of rings, J.
Algebra 176(1995) 124127], Sharma and Bhatwadekar defined a
graph on $R$, $\Gamma(R)$, with vertices as elements of $R$, where
two distinct vertices $a$ and $b$ are adjacent if and only if $Ra
+ Rb = R$. In this paper, we consider a subgraph $\Gamma_2(R)$ of
$\Gamma(R)$ which consists of nonunit elements. We investigate
the behavior of $\Gamma_2(R)$ and $\Gamma_2(R) \setminus \operatorname{J}(R)$,
where $\operatorname{J}(R)$ is the Jacobson radical of $R$. We associate the
ring properties of $R$, the graph properties of $\Gamma_2(R)$ and
the topological properties of $\operatorname{Max}(R)$. Diameter, girth, cycles
and dominating sets are investigated and the algebraic and the
topological characterizations are given for graphical properties
of these graphs.


424  A Note on Amenability of Locally Compact Quantum Groups Sołtan, Piotr M.; Viselter, Ami
In this short note we introduce a notion called ``quantum injectivity''
of locally compact quantum groups, and prove that it is equivalent
to amenability of the dual. Particularly, this provides a new characterization
of amenability of locally compact groups.


431  The Rasmussen Invariant, Fourgenus and Threegenus of an Almost Positive Knot Are Equal Tagami, Keiji
An oriented link is positive if it has a link diagram whose crossings are all positive.
An oriented link is almost positive if it is not positive and has a link diagram with exactly one negative crossing.
It is known that the Rasmussen invariant, $4$genus and $3$genus of a positive knot are equal.
In this paper, we prove that the Rasmussen invariant, $4$genus and $3$genus of an almost positive knot are equal.
Moreover, we determine the Rasmussen invariant of an almost positive knot in terms of its almost positive knot diagram.
As corollaries, we prove that all almost positive knots are not homogeneous, and there is no almost positive knot of $4$genus one.


439  The Fixed Point Locus of the Verschiebung on $\mathcal{M}_X(2, 0)$ for Genus2 Curves $X$ in Charateristic $2$ Yang, YanHong
We prove that for every ordinary genus$2$ curve $X$ over a finite
field $\kappa$ of characteristic $2$ with
$\textrm{Aut}(X/\kappa)=\mathbb{Z}/2\mathbb{Z} \times S_3$, there exist
$\textrm{SL}(2,\kappa[\![s]\!])$representations of $\pi_1(X)$ such
that the image of $\pi_1(\overline{X})$ is infinite. This result
produces a family of examples similar to Laszlo's counterexample
to de Jong's question regarding the finiteness of the geometric
monodromy of representations of the fundamental group.


449  ZLamenability Constants of Finite Groups with Two Character Degrees Alaghmandan, Mahmood; Choi, Yemon; Samei, Ebrahim
We calculate the exact amenability constant of the centre of
$\ell^1(G)$ when $G$ is one of the following classes of finite group:
dihedral; extraspecial; or Frobenius with abelian complement and
kernel. This is done using a formula which applies to all finite
groups with two character degrees. In passing, we answer in the
negative a question raised in work of the third author with Azimifard
and Spronk (J. Funct. Anal. 2009).


463  Constructive Proof of Carpenter's Theorem Bownik, Marcin; Jasper, John
We give a constructive proof of Carpenter's Theorem due to Kadison.
Unlike the original proof our approach also yields the
real case of this theorem.


477  On Set Theoretically and Cohomologically Complete Intersection Ideals Eghbali, Majid
Let $(R,\mathfrak m)$ be a local ring and $\mathfrak a$ be an ideal of $R$. The inequalities
\[
\operatorname{ht}(\mathfrak a) \leq \operatorname{cd}(\mathfrak a,R) \leq
\operatorname{ara}(\mathfrak a) \leq
l(\mathfrak a) \leq \mu(\mathfrak a)
\]
are known. It is an interesting and longstanding problem to find
out the cases giving equality. Thanks to the formal grade we give
conditions in which the above inequalities become
equalities.


485  Fourier Coefficients of Vectorvalued Modular Forms of Dimension $2$ Franc, Cameron; Mason, Geoffrey
We prove the following Theorem. Suppose that $F=(f_1, f_2)$ is a $2$dimensional vectorvalued modular form
on $\operatorname{SL}_2(\mathbb{Z})$ whose component functions $f_1, f_2$ have rational Fourier coefficients
with bounded denominators. Then $f_1$ and $f_2$ are classical modular forms on a congruence subgroup of the modular group.


495  Jeśmanowicz' Conjecture with Congruence Relations. II Fujita, Yasutsugu; Miyazaki, Takafumi
Let $a,b$ and $c$ be primitive Pythagorean numbers such that
$a^{2}+b^{2}=c^{2}$ with $b$ even.
In this paper, we show that if $b_0 \equiv \epsilon \pmod{a}$
with $\epsilon \in \{\pm1\}$
for certain positive divisors $b_0$ of $b$,
then the Diophantine equation $a^{x}+b^{y}=c^z$ has only the
positive solution $(x,y,z)=(2,2,2)$.


506  On Braided and Ribbon Unitary Fusion Categories Galindo, César
We prove that every braiding over a unitary fusion category is
unitary and every unitary braided fusion category admits a unique
unitary ribbon structure.


511  Simplicity of Partial Skew Group Rings of Abelian Groups Gonçalves, Daniel
Let $A$ be a ring with local units, $E$ a set of local units for $A$,
$G$ an abelian group and $\alpha$ a partial action of $G$ by ideals of
$A$ that contain local units.
We show that $A\star_{\alpha} G$ is simple if and only if $A$ is
$G$simple and the center of the corner $e\delta_0 (A\star_{\alpha} G)
e \delta_0$ is a field for all $e\in E$. We apply the result to
characterize simplicity of partial skew group rings in two cases,
namely for partial skew group rings arising from partial actions by
clopen subsets of a compact set and partial actions on the set level.


520  Maximizing the Index of Trees with Given Domination Number Guo, Guangquan; Wang, Guoping
The index of a graph $G$ is the maximum
eigenvalue of its adjacency matrix $A(G)$. In this paper we
characterize the extremal tree with given
domination number that attains the maximum index.


526  On $3$manifolds with Torus or Klein Bottle Category Two Heil, Wolfgang; Wang, Dongxu
A subset $W$ of a closed manifold $M$ is $K$contractible, where $K$
is a torus or Kleinbottle, if the inclusion $W\rightarrow M$ factors
homotopically through a map to $K$. The image of $\pi_1 (W)$ (for any
base point) is a subgroup of $\pi_1 (M)$ that is isomorphic to a
subgroup of a quotient group of $\pi_1 (K)$. Subsets of $M$ with this
latter property are called $\mathcal{G}_K$contractible. We obtain a
list of the closed $3$manifolds that can be covered by two open
$\mathcal{G}_K$contractible subsets. This is applied to obtain a list
of the possible closed prime $3$manifolds that can be covered by two
open $K$contractible subsets.


538  Infinite Families of $A_4$Sextic Polynomials Ide, Joshua; Jones, Lenny
In this article we develop a test to determine whether a sextic
polynomial that is irreducible over $\mathbb{Q}$ has Galois group isomorphic
to the alternating group $A_4$. This test does not involve the
computation of resolvents, and we use this test to construct several
infinite families of such polynomials.


546  Compact Operators in Regular LCQ Groups Kalantar, Mehrdad
We show that a regular locally compact quantum group $\mathbb{G}$ is discrete
if and only if $\mathcal{L}^{\infty}(\mathbb{G})$ contains nonzero compact operators on
$\mathcal{L}^{2}(\mathbb{G})$.
As a corollary we classify all discrete quantum groups among
regular locally compact quantum groups $\mathbb{G}$ where
$\mathcal{L}^{1}(\mathbb{G})$ has the RadonNikodym property.


551  Asymptotic Improvements of Lower Bounds for the Least Common Multiples of Arithmetic Progressions Kane, Daniel M.; Kominers, Scott Duke
For relatively prime positive integers $u_0$ and $r$, we consider the
least common multiple $L_n:=\mathop{\textrm{lcm}}(u_0,u_1,\dots, u_n)$ of the finite
arithmetic progression $\{u_k:=u_0+kr\}_{k=0}^n$. We derive new lower
bounds on $L_n$ that improve upon those obtained previously when
either $u_0$ or $n$ is large. When $r$ is prime, our best bound is
sharp up to a factor of $n+1$ for $u_0$ properly chosen, and is also
nearly sharp as $n\to\infty$.


562  Note on the Grothendieck Group of Subspaces of Rational Functions and Shokurov's Cartier bdivisors Kaveh, Kiumars; Khovanskii, A. G.
In a previous paper the authors developed an intersection theory for
subspaces of rational functions on an algebraic variety $X$
over $\mathbf{k} = \mathbb{C}$. In this short note, we first extend this intersection
theory to an arbitrary algebraically closed ground field $\mathbf{k}$.
Secondly we give an isomorphism between the group of Cartier
$b$divisors on the birational class of $X$
and the Grothendieck group
of the semigroup of subspaces of rational functions on $X$. The
constructed isomorphism moreover
preserves the intersection numbers. This provides an alternative point
of view on Cartier $b$divisors and their intersection theory.


573  Some Results on the Domination Number of a Zerodivisor Graph Kiani, Sima; Maimani, Hamid Reza; Nikandish, Reza
In this paper, we investigate the domination, total domination and
semitotal domination numbers of a zerodivisor graph of a
commutative Noetherian ring. Also, some relations between the
domination numbers of $\Gamma(R/I)$ and $\Gamma_I(R)$, and the
domination numbers of $\Gamma(R)$ and $\Gamma(R[x,\alpha,\delta])$,
where $R[x,\alpha,\delta]$ is the Ore extension of $R$, are studied.


579  On the Hereditary Paracompactness of Locally Compact, Hereditarily Normal Spaces Larson, Paul; Tall, Franklin D.
We establish that if it is consistent that there is a
supercompact cardinal, then it is consistent that every locally
compact, hereditarily normal space which does not include a perfect
preimage of $\omega_1$ is hereditarily paracompact.


585  Short Probabilistic Proof of the BrascampLieb and Barthe Theorems Lehec, Joseph
We give a short proof of the BrascampLieb theorem, which asserts that
a certain general form of Young's convolution inequality is saturated
by Gaussian functions. The argument is inspired by Borell's stochastic
proof of the PrékopaLeindler inequality and applies also to the
reversed BrascampLieb inequality, due to Barthe.


598  Interpolation of Morrey Spaces on Metric Measure Spaces Lu, Yufeng; Yang, Dachun; Yuan, Wen
In this article, via the classical complex interpolation method
and some interpolation methods traced to Gagliardo,
the authors obtain an interpolation theorem for
Morrey spaces on quasimetric measure spaces, which generalizes
some known results on ${\mathbb R}^n$.


609  Jacobson Radicals of Skew Polynomial Rings of Derivation Type NasrIsfahani, Alireza
We provide necessary and sufficient conditions for a skew polynomial ring of derivation type to be semiprimitive, when the base ring has no nonzero nil ideals. This extends existing results on the Jacobson radical of skew polynomial rings of derivation
type.


614  A Note on the Weierstrass Preparation Theorem in Quasianalytic Local Rings Parusiński, Adam; Rolin, JeanPhilippe
Consider quasianalytic local rings of germs of smooth functions closed
under composition, implicit equation, and monomial division. We show
that if the Weierstrass Preparation Theorem holds in such a ring then
all elements of it are germs of analytic functions.


621  Combinatorially Factorizable Cryptic Inverse Semigroups Petrich, Mario
An inverse semigroup $S$ is combinatorially factorizable if $S=TG$
where $T$ is a combinatorial (i.e., $\mathcal{H}$ is the equality
relation) inverse subsemigroup of $S$ and $G$ is a subgroup of $S$.
This concept was introduced and studied by Mills, especially in the
case when $S$ is cryptic (i.e., $\mathcal{H}$ is a congruence on
$S$). Her approach is mainly analytical considering subsemigroups of
a cryptic inverse semigroup.


631  Indicators, Chains, Antichains, Ramsey Property Sokić, Miodrag
We introduce two Ramsey classes of finite relational structures. The first
class contains finite structures of the form $(A,(I_{i})_{i=1}^{n},\leq
,(\preceq _{i})_{i=1}^{n})$ where $\leq $ is a total ordering on $A$ and $%
\preceq _{i}$ is a linear ordering on the set $\{a\in A:I_{i}(a)\}$. The
second class contains structures of the form $(A,\leq
,(I_{i})_{i=1}^{n},\preceq )$ where $(A,\leq )$ is a weak ordering and $%
\preceq $ is a linear ordering on $A$ such that $A$ is partitioned by $%
\{a\in A:I_{i}(a)\}$ into maximal chains in the partial ordering $\leq $ and
each $\{a\in A:I_{i}(a)\}$ is an interval with respect to $\preceq $.


640  Equilateral Sets and a Schütte Theorem for the $4$norm Swanepoel, Konrad J.
A wellknown theorem of Schütte (1963) gives a sharp lower bound for
the ratio of the maximum and minimum distances between $n+2$ points in
$n$dimensional Euclidean space.
In this note we adapt Bárány's elegant proof (1994) of this theorem to the space $\ell_4^n$.
This gives a new proof that the largest cardinality of an equilateral
set in $\ell_4^n$ is $n+1$, and gives a constructive bound for an
interval $(4\varepsilon_n,4+\varepsilon_n)$ of values of $p$ close to $4$ for which it is known that the largest cardinality of an equilateral set in $\ell_p^n$ is $n+1$.


648  On the ${\mathcal F}{\Phi}$Hypercentre of Finite Groups Tang, Juping; Miao, Long
Let $G$ be a finite group, $\mathcal F$ a class of groups.
Then $Z_{{\mathcal F}{\Phi}}(G)$ is the ${\mathcal F}{\Phi}$hypercentre
of $G$ which is the product of all normal subgroups of $G$ whose
nonFrattini $G$chief factors are $\mathcal F$central in $G$. A
subgroup $H$ is called $\mathcal M$supplemented in a finite group
$G$, if there exists a subgroup $B$ of $G$ such that $G=HB$ and
$H_1B$ is a proper subgroup of $G$ for any maximal subgroup $H_1$
of $H$. The main purpose of this paper is to prove: Let $E$ be a
normal subgroup of a group $G$. Suppose that every noncyclic
Sylow
subgroup $P$ of $F^{*}(E)$ has a subgroup $D$ such that
$1\lt D\lt P$ and every subgroup $H$ of $P$ with order $H=D$
is
$\mathcal M$supplemented in $G$, then $E\leq Z_{{\mathcal
U}{\Phi}}(G)$.


658  Admissibility of Local Systems for some Classes of Line Arrangements Thang, Nguyen Tat
Let $\mathcal{A}$ be a line arrangement in the complex
projective plane $\mathbb{P}^2$ and let $M$ be its complement. A rank one
local system $\mathcal{L}$ on $M$ is admissible if roughly speaking
the cohomology groups
$H^m(M,\mathcal{L})$ can be computed directly from the cohomology
algebra $H^{*}(M,\mathbb{C})$. In this work, we give a sufficient
condition for the admissibility of all rank one local systems on
$M$. As a result, we obtain some properties of the characteristic
variety $\mathcal{V}_1(M)$ and the Resonance variety $\mathcal{R}_1(M)$.


673  Complexifying Lie Group Actions on Homogeneous Manifolds of Noncompact Dimension Two Ahmadi, S. Ruhallah; Gilligan, Bruce
If $X$ is a connected complex manifold with $d_X = 2$ that admits a (connected) Lie group $G$
acting transitively as a group of holomorphic transformations, then the action extends to an action of the
complexification $\widehat{G}$ of $G$ on $X$ except when
either the unit disk in the complex plane
or a strictly pseudoconcave homogeneous complex manifold is
the base or fiber of some homogeneous fibration of $X$.


683  Topological Games and Alster Spaces Aurichi, Leandro F.; Dias, Rodrigo R.
In this paper we study connections between topological games
such
as Rothberger, Menger and compactopen, and relate these games
to
properties involving covers by $G_\delta$ subsets. The results
include:
(1) If Two has a winning strategy in the Menger
game on a regular space $X$, then $X$ is an Alster space.
(2) If Two has a winning strategy in the Rothberger game on a
topological space $X$, then the $G_\delta$topology on $X$ is
Lindelöf.
(3) The Menger game and the compactopen game are (consistently)
not
dual.


697  On the Monodromy of Milnor Fibers of Hyperplane Arrangements Bailet, Pauline
We describe a general setting where the monodromy action on the first
cohomology group of the Milnor fiber of a hyperplane arrangement is
the identity.


708  Strong Asymptotic Freeness for Free Orthogonal Quantum Groups Brannan, Michael
It is known that the normalized standard generators of the free
orthogonal quantum group $O_N^+$ converge in distribution to a free
semicircular system as $N \to \infty$. In this note, we
substantially improve this convergence result by proving that, in
addition to distributional convergence, the operator norm of any
noncommutative polynomial in the normalized standard generators of
$O_N^+$ converges as $N \to \infty$ to the operator norm of the
corresponding noncommutative polynomial in a standard free
semicircular system. Analogous strong convergence results are obtained
for the generators of free unitary quantum groups. As applications of
these results, we obtain a matrixcoefficient version of our strong
convergence theorem, and we recover a well known $L^2$$L^\infty$ norm
equivalence for noncommutative polynomials in free semicircular
systems.


721  Classification of Integral Modular Categories of FrobeniusPerron Dimension $pq^4$ and $p^2q^2$ Bruillard, Paul; Galindo, César; Hong, SeungMoon; Kashina, Yevgenia; Naidu, Deepak; Natale, Sonia; Plavnik, Julia Yael; Rowell, Eric C.
We classify integral modular categories of dimension $pq^4$ and $p^2q^2$,
where
$p$ and $q$ are distinct primes. We show that such categories are always
grouptheoretical except for categories of dimension $4q^2$.
In these cases there are
wellknown examples of nongrouptheoretical categories, coming from
centers of
TambaraYamagami categories and quantum groups. We show that a
nongrouptheoretical integral modular category of dimension $4q^2$ is
equivalent to either one of these wellknown examples or is of dimension
$36$ and is twistequivalent to fusion categories arising from a
certain quantum group.


735  On the Theorem of the Primitive Element with Applications to the Representation Theory of Associative and Lie Algebras Cagliero, Leandro; Szechtman, Fernando
We describe of all finite
dimensional uniserial representations of a commutative associative
(resp. abelian Lie) algebra over a perfect (resp. sufficiently
large perfect) field. In the Lie case the size of the field
depends on the answer to following question, considered and solved
in this paper. Let $K/F$ be a finite separable field extension
and
let $x,y\in K$. When is $F[x,y]=F[\alpha x+\beta y]$ for some
nonzero elements $\alpha,\beta\in F$?


749  Geometric Perspective on Piecewise Polynomiality of Double Hurwitz Numbers Cavalieri, Renzo; Marcus, Steffen
We describe double Hurwitz numbers as intersection numbers on the
moduli space of curves $\overline{\mathcal{M}}_{g,n}$. Using a result on the
polynomiality of intersection numbers of psi classes with the Double
Ramification Cycle, our formula explains the polynomiality in chambers
of double Hurwitz numbers, and the wall crossing phenomenon in terms
of a variation of correction terms to the $\psi$ classes. We
interpret this as suggestive evidence for polynomiality of the Double
Ramification Cycle (which is only known in genera $0$ and $1$).


765  Helicoidal Minimal Surfaces in a Finsler Space of Randers Type da Silva, Rosângela Maria; Tenenblat, Keti
We consider the Finsler space $(\bar{M}^3, \bar{F})$ obtained by
perturbing the Euclidean metric of $\mathbb{R}^3$ by a rotation. It
is the open region of $\mathbb{R}^3$ bounded by a cylinder with a
Randers metric. Using the BusemannHausdorff volume form, we
obtain the differential equation that characterizes the helicoidal
minimal surfaces in $\bar{M}^3$. We prove that the helicoid is a
minimal surface in $\bar{M}^3$, only if the axis of the helicoid
is the axis of the cylinder. Moreover, we prove that, in the
Randers space $(\bar{M}^3, \bar{F})$, the only minimal
surfaces in the Bonnet family, with fixed axis $O\bar{x}^3$, are the catenoids
and the helicoids.


780  Measures of Noncompactness in Regular Spaces Erzakova, Nina A.
Previous results by the author on the connection
between three of measures
of noncompactness obtained for $L_p$, are extended
to regular spaces of measurable
functions.
An example of advantage
in some cases one of them in comparison with another is given.
Geometric characteristics of regular spaces are determined.
New theorems for $(k,\beta)$boundedness of partially additive
operators are proved.


794  New Characterizations of the Weighted Composition Operators Between Bloch Type Spaces in the Polydisk Fang, ZhongShan; Zhou, ZeHua
We give some new characterizations for compactness of weighted
composition operators $uC_\varphi$ acting on Blochtype spaces in
terms of the power of the components of $\varphi,$ where $\varphi$
is a holomorphic selfmap of the polydisk $\mathbb{D}^n,$ thus
generalizing the results obtained by Hyvärinen and
Lindström in 2012.


803  Free Locally Convex Spaces and the $k$space Property Gabriyelyan, S. S.
Let $L(X)$ be the free locally convex space over a Tychonoff space $X$. Then $L(X)$ is a $k$space if and only if $X$ is a countable discrete space. We prove also that $L(D)$ has uncountable tightness for every uncountable discrete space $D$.


810  Uniqueness of Preduals in Spaces of Operators Godefroy, G.
We show that if $E$ is a separable reflexive space, and $L$ is a weakstar closed linear subspace of
$L(E)$ such that $L\cap K(E)$ is weakstar dense in $L$, then $L$ has a unique isometric predual. The proof relies on basic topological arguments.


814  On Global Dimensions of Tree Type Finite Dimensional Algebras Hou, Ruchen
A formula is provided to
explicitly describe global dimensions of all kinds of tree type
finite dimensional $k$algebras for $k$ an algebraic closed field.
In particular, it is pointed out that if the underlying tree type
quiver has $n$ vertices, then the maximum of possible global
dimensions is $n1$.


821  Real Hypersurfaces in Complex TwoPlane Grassmannians with Reeb Parallel Structure Jacobi Operator Jeong, Imsoon; Kim, Seonhui; Suh, Young Jin
In this paper we give a characterization of a real hypersurface of
Type~$(A)$ in complex twoplane Grassmannians ${ { {G_2({\mathbb
C}^{m+2})} } }$, which means a
tube over a totally geodesic $G_{2}(\mathbb C^{m+1})$ in
${G_2({\mathbb C}^{m+2})}$, by
the Reeb parallel structure Jacobi operator ${\nabla}_{\xi}R_{\xi}=0$.


834  Restriction Operators Acting on Radial Functions on Vector Spaces Over Finite Fields Koh, Doowon
We study $L^pL^r$ restriction estimates for
algebraic varieties $V$ in the case when restriction operators act on
radial functions in the finite field setting.
We show that if the varieties $V$ lie in odd dimensional vector
spaces over finite fields, then the conjectured restriction estimates
are possible for all radial test functions.
In addition, assuming that the varieties $V$ are defined in even
dimensional spaces and have few intersection points with the sphere
of zero radius, we also obtain the conjectured exponents for all
radial test functions.


845  Factorisation of Twovariable $p$adic $L$functions Lei, Antonio
Let $f$ be a modular form which is nonordinary at $p$. Loeffler has
recently constructed four twovariable $p$adic $L$functions
associated to $f$. In the case where $a_p=0$, he showed that, as in
the onevariable case, Pollack's plus and minus splitting applies to
these new objects. In this article, we show that such a splitting can
be generalised to the case where $a_p\ne0$ using Sprung's logarithmic
matrix.


853  On the Bound of the $\mathrm{C}^*$ Exponential Length Pan, Qingfei; Wang, Kun
Let $X$ be a compact Hausdorff space. In this paper, we give an
example to show that there is $u\in \mathrm{C}(X)\otimes \mathrm{M}_n$
with $\det (u(x))=1$ for all $x\in X$ and $u\sim_h 1$ such that the
$\mathrm{C}^*$ exponential length of $u$
(denoted by $cel(u)$) can not be controlled by
$\pi$. Moreover, in simple inductive limit $\mathrm{C}^*$algebras,
similar examples also exist.


870  A Short Note on Short Pants Parlier, Hugo
It is a theorem of Bers that any closed hyperbolic surface admits a pants decomposition consisting of curves of bounded length where the bound only depends on the topology of the surface. The question of the quantification of the optimal constants has been well studied and the best upper bounds to date are linear in genus, a theorem of Buser and Seppälä. The goal of this note is to give a short proof of a linear upper bound which slightly improve the best known bound.


877  On Convolutions of Convex Sets and Related Problems Schoen, Tomasz
We prove some results concerning covolutions, the
additive energy and sumsets of convex sets and its generalizations. In
particular, we show that if a set $A=\{a_1,\dots,a_n\}_\lt \subseteq
\mathbb R$ has
the property that for every fixed
$1\leqslant d\lt n,$ all differences $a_ia_{id}$, $d\lt i\lt n,$ are distinct, then
$A+A\gg A^{3/2+c}$ for a constant $c\gt 0.$


884  $m$embedded Subgroups and $p$nilpotency of Finite Groups Xu, Yong; Zhang, Xinjian
Let $A$ be a subgroup of a finite group $G$ and $\Sigma : G_0\leq
G_1\leq\cdots \leq G_n$ some subgroup series of $G$. Suppose that
for each pair $(K,H)$ such that $K$ is a maximal subgroup of $H$ and
$G_{i1}\leq K \lt H\leq G_i$, for some $i$, either $A\cap H = A\cap K$
or $AH = AK$. Then $A$ is said to be $\Sigma$embedded in $G$; $A$
is said to be $m$embedded in $G$ if $G$ has a subnormal subgroup
$T$ and a $\{1\leq G\}$embedded subgroup $C$ in $G$ such that $G =
AT$ and $T\cap A\leq C\leq A$. In this article, some sufficient
conditions for a finite group $G$ to be $p$nilpotent are given
whenever all subgroups with order $p^{k}$ of a Sylow $p$subgroup of
$G$ are $m$embedded for a given positive integer $k$.

