Search results for "abelian"
showing 10 items of 208 documents
Some new (s,k,?)-translation transversal designs with non-abelian translation group
1989
For λ >1 and many values of s andk, we give a construction of (s,k,λ)-partitions of finite non-abelian p-groups and of Frobenius groups with non-abelian kernel. These groups are associated with translation transversl designs of the same parameters.
Some Hadamard designs with parameters (71,35,17)
2002
Up to isomorphisms there are precisely eight symmetric designs with parameters (71, 35, 17) admitting a faithful action of a Frobenius group of order 21 in such a way that an element of order 3 fixes precisely 11 points. Five of these designs have 84 and three have 420 as the order of the full automorphism group G. If |G| = 420, then the structure of G is unique and we have G = (Frob21 × Z5):Z4. In this case Z(G) = 〈1〉, G′ has order 35, and G induces an automorphism group of order 6 of Z7. If |G| = 84, then Z(G) is of order 2, and in precisely one case a Sylow 2-subgroup is elementary abelian. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 144–149, 2002; DOI 10.1002/jcd.996
Locally nilpotent derivations of rings graded by an abelian group
2019
International audience
A note on easy and efficient computation of full abelian periods of a word
2016
Constantinescu and Ilie (Bulletin of the EATCS 89, 167-170, 2006) introduced the idea of an Abelian period with head and tail of a finite word. An Abelian period is called full if both the head and the tail are empty. We present a simple and easy-to-implement $O(n\log\log n)$-time algorithm for computing all the full Abelian periods of a word of length $n$ over a constant-size alphabet. Experiments show that our algorithm significantly outperforms the $O(n)$ algorithm proposed by Kociumaka et al. (Proc. of STACS, 245-256, 2013) for the same problem.
Nilpotent and abelian Hall subgroups in finite groups
2015
[EN] We give a characterization of the finite groups having nilpotent or abelian Hall pi-subgroups that can easily be verified using the character table.
La singularité de O’Grady
2006
Let M 2 v M_{2v} be the moduli space of semistable sheaves with Mukai vector 2 v 2v on an abelian or K 3 K3 surface where v v is primitive such that ⟨ v , v ⟩ = 2 \langle v,v \rangle =2 . We show that the blow-up of the reduced singular locus of M 2 v M_{2v} provides a symplectic resolution of singularities. This provides a direct description of O’Grady’s resolutions of M K 3 ( 2 , 0 , 4 ) M_{K3}(2,0,4) and M A b ( 2 , 0 , 2 ) M_{Ab}(2,0,2) . Résumé. Soit M 2 v M_{2v} l’espace de modules des faisceaux semi-stables de vecteur de Mukai 2 v 2v sur une surface K 3 K3 ou abélienne où v v est primitif tel que ⟨ v , v ⟩ = 2 \langle v,v \rangle =2 . Nous montrons que l’éclatement de M 2 v M_{2v} le…
Abelian projection and studies of gauge-variant quantities in lattice QCD without gauge fixing
1996
We suggest a new (dynamical) Abelian projection of the lattice QCD. It contains no gauge condition imposed on gauge fields so that Gribov copying is avoided. Configurations of gauge fields that turn into monopoles in the Abelian projection can be classified in a gauge invariant way. In the continuum limit, the theory respects the Lorentz invariance. A similar dynamical reduction of the gauge symmetry is proposed for studies of gauge-variant correlators (like a gluon propagator) in lattice QCD. Though the procedure is harder for numerical simulations, it is free of gauge fixing artifacts, like the Gribov horizon and copies.
Module categories of finite Hopf algebroids, and self-duality
2017
International audience; We characterize the module categories of suitably finite Hopf algebroids (more precisely, $X_R$-bialgebras in the sense of Takeuchi (1977) that are Hopf and finite in the sense of a work by the author (2000)) as those $k$-linear abelian monoidal categories that are module categories of some algebra, and admit dual objects for "sufficiently many" of their objects. Then we proceed to show that in many situations the Hopf algebroid can be chosen to be self-dual, in a sense to be made precise. This generalizes a result of Pfeiffer for pivotal fusion categories and the weak Hopf algebras associated to them.
Heavy-tail properties of relaxation time distributions underlying the Havriliak–Negami and the Kohlrausch–Williams–Watts relaxation patterns
2007
Abstract A detailed discussion of asymptotic properties of the Havriliak–Negami and the Kohlrausch–Williams–Watts relaxation time distributions is presented. The heavy-tail property of the Havriliak–Negami relaxation time distribution, leading to the infinite mean relaxation time, is discussed. In contrast, the existence of the finite mean relaxation time for the Kohlrausch–Williams–Watts response is shown. The discussion of the Cole–Davidson and the Cole–Cole cases is also included. Using the Tauberian theorems we show that these properties are determined directly by the asymptotic behavior of the considered empirical functions.
Albanese Maps and Fundamental Groups of Varieties With Many Rational Points Over Function Fields
2020
We investigate properties of the Albanese map and the fundamental group of a complex projective variety with many rational points over some function field, and prove that every linear quotient of the fundamental group of such a variety is virtually abelian, as well as that its Albanese map is surjective, has connected fibres, and has no multiple fibres in codimension one.