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1.
In this paper, we establish several decidability results for pseudovariety joins of the form
\sf Vú\sf W{\sf V}\vee{\sf W}
, where
\sf V{\sf V}
is a subpseudovariety of
\sf J{\sf J}
or the pseudovariety
\sf R{\sf R}
. Here,
\sf J{\sf J}
(resp.
\sf R{\sf R}
) denotes the pseudovariety of all
J{\cal J}
-trivial (resp.
?{\cal R}
-trivial) semigroups. In particular, we show that the pseudovariety
\sf Vú\sf W{\sf V}\vee{\sf W}
is (completely) κ-tame when
\sf V{\sf V}
is a subpseudovariety of
\sf J{\sf J}
with decidable κ-word problem and
\sf W{\sf W}
is (completely) κ-tame. Moreover, if
\sf W{\sf W}
is a κ-tame pseudovariety which satisfies the pseudoidentity x1 ⋯ xryω+1ztω = x1 ⋯ xryztω, then we prove that
\sf Rú\sf W{\sf R}\vee{\sf W}
is also κ-tame. In particular the joins
\sf Rú\sf Ab{\sf R}\vee{\sf Ab}
,
\sf Rú\sf G{\sf R}\vee{\sf G}
,
\sf Rú\sf OCR{\sf R}\vee{\sf OCR}
, and
\sf Rú\sf CR{\sf R}\vee{\sf CR}
are decidable. 相似文献
2.
Franki Dillen Johan Fastenakels Joeri Van der Veken Luc Vrancken 《Monatshefte für Mathematik》2007,40(1):89-96
In this article we study surfaces in
\Bbb S2×\Bbb R {\Bbb S}^2\times {\Bbb R}
for which the unit normal makes a constant angle with the
\Bbb R {\Bbb R}
-direction. We give a complete classification for surfaces satisfying this simple geometric condition. 相似文献
3.
Qilin Yang 《Monatshefte für Mathematik》2008,24(4):79-95
We prove that the Morse decomposition in the sense of Kirwan and semistable decomposition in the sense of GIT of a
\Bbb C*{\Bbb C}^{\ast}
-K?hler manifold coincide if the moment map is proper and if the fixed points set
X\Bbb C*X^{{\Bbb C}^{\ast}}
has a finite number of connected components. For general K?hler space with holomorphic action of a complex reductive group
G, if every component of the moment map is proper, the two decompositions also coincide if each semistable piece is Zariski
open in its topological closure and the moment map square is minimal degenerate Morse function in the sense of Kirwan. 相似文献
4.
The algebra Bp(\Bbb R){\cal B}_p({\Bbb R}), p ? (1,¥)\{2}p\in (1,\infty )\setminus \{2\}, consisting of all measurable sets in \Bbb R{\Bbb R} whose characteristic function is a Fourier p-multiplier, forms an algebra of sets containing many interesting and non-trivial elements (e.g. all intervals and their finite unions, certain periodic sets, arbitrary countable unions of dyadic intervals, etc.). However, Bp(\Bbb R){\cal B}_p({\Bbb R}) fails to be a s\sigma -algebra. It has been shown by V. Lebedev and A. Olevskii [4] that if E ? Bp(\Bbb R)E\in {\cal B}_p({\Bbb R}), then E must coincide a.e. with an open set, a remarkable topological constraint on E. In this note we show if $2 < p < \infty $2 < p < \infty , then there exists E ? Bp(\Bbb R)E\in {\cal B}_p({\Bbb R}) which is not in Bq(\Bbb R){\cal B}_q({\Bbb R}) for any q > pq>p. 相似文献
5.
Let G be a finitely presented pro-
C{\cal C}
group with discrete relations. We prove that the kernel of an epimorphism of G to
[^(\Bbb Z)]C\hat{\Bbb Z}_{\cal C}
is topologically finitely generated if G does not contain a free pro-
C{\cal C}
group of rank 2. In the case of pro-p groups the result is due to J. Wilson and E. Zelmanov and does not require that the relations are discrete ([15], [17]).For a pro-p group G of type FPm we define a homological invariant C{\cal C}
groups, pro-p groups, homological type FPm, finite presentabilityBoth authors are partially supported by CNPq, Brazil. 相似文献
6.
The notion of pseudo-randomness of subsets of
\mathbb Zn{\mathbb Z_n} is defined, and the measures of pseudo-randomness are introduced. Then a construction (based on the use of hybrid character
sums) will be presented for subsets of
\mathbb Zp{\mathbb Z_p} with strong pseudo-random properties. 相似文献
7.
In the present part (II) we will deal with the group
\mathbb G = \mathbb Zn{\mathbb G = \mathbb Z^n} , and we will study the effect of linear transformations on minimal covering and maximal packing densities of finite sets
A ì \mathbb Zn{\mathcal A \subset {\mathbb Z}^n} . As a consequence, we will be able to show that the set of all densities for sets A{\mathcal A} of given cardinality is closed, and to characterize four-element sets
A ì \mathbb Zn{\mathcal A \subset {\mathbb Z}^n} which are “tiles”. The present work will be largely independent of the first part (I) presented in [4]. 相似文献
8.
Fukun Zhao Leiga Zhao Yanheng Ding 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,15(6):495-511
This paper is concerned with the following periodic Hamiltonian elliptic system
{l-Du+V(x)u=g(x,v) in \mathbbRN,-Dv+V(x)v=f(x,u) in \mathbbRN,u(x)? 0 and v(x)?0 as |x|?¥,\left \{\begin{array}{l}-\Delta u+V(x)u=g(x,v)\, {\rm in }\,\mathbb{R}^N,\\-\Delta v+V(x)v=f(x,u)\, {\rm in }\, \mathbb{R}^N,\\ u(x)\to 0\, {\rm and}\,v(x)\to0\, {\rm as }\,|x|\to\infty,\end{array}\right. 相似文献
9.
Lars Olsen 《Monatshefte für Mathematik》2011,25(2):89-117
In this paper we study the Hausdorff and packing dimensions and the Rényi dimensions of random self-affine multifractal Sierpinski
sponges in
\mathbbRd{\mathbb{R}^{d}}. 相似文献
10.
Unl?sbarkeit der Gleichung axn + byn = zn\alpha x^n + \beta y^n = z^n und Gleichverteilung von
We show that the unsolvability of the Diophantine equation
axn + byn = zn\alpha x^n + \beta y^n = z^n
is equivalent to a good uniform distribution of the set
{ n ?{axn + byn} }\{ \root n \of{\alpha x^n + \beta y^n} \}
. The proof depends on the asymptotic evaluation of the Gauss sum
?x, y e (n ?{axn + byn})\sum_{x, y} e (\root n \of{\alpha x^n + \beta y^n})
. 相似文献
11.
By a totally regular parallelism of the real projective 3-space
P3:=PG(3, \mathbb R){\Pi_3:={{\rm PG}}(3, \mathbb {R})} we mean a family T of regular spreads such that each line of Π
3 is contained in exactly one spread of T. For the investigation of totally regular parallelisms the authors mainly employ Klein’s correspondence λ of line geometry and the polarity π
5 associated with the Klein quadric H
5 (for details see Chaps. 1 and 3). The λ-image of a totally regular parallelism T is a hyperflock of H
5, i.e., a family H of elliptic subquadrics of H
5 such that each point of H
5 is on exactly one subquadric of H. Moreover, {p5(span l(X))|X ? T}=:HT{\{\pi_5({{\rm span}} \,\lambda(\mathcal {X}))\vert\mathcal {X}\in\bf{T}\}=:\mathcal {H}_{\bf{T}}} is a hyperflock determining line set, i.e., a set Z{\mathcal {Z}} of 0-secants of H
5 such that each tangential hyperplane of H
5 contains exactly one line of Z{\mathcal {Z}} . We say that dim(span HT)=:dT{{{\rm dim}}({{\rm span}}\,\mathcal {H}_{\bf{T}})=:d_{\bf{T}}} is the dimension of
T and that T is a d
T
- parallelism. Clifford parallelisms and 2-parallelisms coincide. The examples of non-Clifford parallelisms exhibited in Betten
and Riesinger [Result Math 47:226–241, 2004; Adv Geom 8:11–32, 2008; J Geom (to appear)] are totally regular and of dimension
3. If G{\mathcal{G}} is a hyperflock determining line set, then {l-1 (p5(X) ?H5) | X ? G}{\{\lambda^{-1}\,{\rm (}\pi_5(X){\,\cap H_5)\,|\, X\in\mathcal{G}\}}} is a totally regular parallelism. In the present paper the authors construct examples of topological (see Definition 1.1)
4- and 5-parallelisms via hyperflock determining line sets. 相似文献
12.
Bernhard Burgstaller 《Monatshefte für Mathematik》2009,265(4):1-11
There exists a separable exact C*-algebra A which contains all separable exact C*-algebras as subalgebras, and for each norm-dense measure μ on A and independent μ-distributed random elements x
1, x
2, ... we have
limn ? ¥\mathbb P(C*(x1,?,xn) is nuclear)=0{\rm {lim}}_{n \rightarrow \infty}\mathbb {P}(C^*(x_1,\ldots,x_n) \mbox{ is nuclear})=0. Further, there exists a norm-dense non-atomic probability measure μ on the Cuntz algebra O2{\mathcal {O}_2} such that for an independent sequence x
1, x
2, ... of μ-distributed random elements x
i
we have
lim infn ? ¥\mathbb P(C*(x1,?,xn) is nuclear)=0{\rm {lim\, inf}}_{n \rightarrow \infty}\mathbb {P}(C^*(x_1,\ldots,x_n) \mbox{ is nuclear})=0. We introduce the notion of the stochastic rank for a unital C*-algebra and prove that the stochastic rank of C([0, 1]
d
) is d. 相似文献
13.
Jiabao Su 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2012,21(2):51-62
We study the existence and multiplicity of nontrivial radial solutions of the quasilinear equation
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