532 research outputs found
Existential questions in (relatively) hyperbolic groups {\it and} Finding relative hyperbolic structures
This arXived paper has two independant parts, that are improved and corrected
versions of different parts of a single paper once named "On equations in
relatively hyperbolic groups".
The first part is entitled "Existential questions in (relatively) hyperbolic
groups". We study there the existential theory of torsion free hyperbolic and
relatively hyperbolic groups, in particular those with virtually abelian
parabolic subgroups. We show that the satisfiability of systems of equations
and inequations is decidable in these groups.
In the second part, called "Finding relative hyperbolic structures", we
provide a general algorithm that recognizes the class of groups that are
hyperbolic relative to abelian subgroups.Comment: Two independant parts 23p + 9p, revised. To appear separately in
Israel J. Math, and Bull. London Math. Soc. respectivel
Some integral inequalities on time scales
In this paper, some new integral inequalities on time scales are presented by
using elementarily analytic methods in calculus of time scales.Comment: 8 page
Accidental parabolics and relatively hyperbolic groups
By constructing, in the relative case, objects analoguous to Rips and Sela's
canonical representatives, we prove that the set of images by morphisms without
accidental parabolic, of a finitely presented group in a relatively hyperbolic
group, is finite, up to conjugacy.Comment: Revision, 24 pages, 4 figure
Cubulating a free-product-by-cyclic group
Let be a torsion-free group and an
automorphism of that preserves this free factor system. We show that when
is fully irreducible and atoroidal relative to this free factor system,
the mapping torus acts relatively
geometrically on a hyperbolic CAT(0) cube complex. This is a generalisation of
a result of Hagen and Wise for hyperbolic free-by-cyclic groups.Comment: 10 figures, incorporated referee suggestions. Final version, to
appear in Alg. Geom. Topo
Relative hyperbolicity of hyperbolic-by-cyclic groups
Let be a torsion-free hyperbolic group and an automorphism of
. We show that there exists a canonical collection of subgroups that are
polynomially growing under , and that the mapping torus of by
is hyperbolic relative to the suspensions of the maximal polynomially
growing subgroups under .Comment: 17 pages, 1 figur
CDM jerk parameter in symmetric teleparallel cosmology
In this paper, we have examined the recently proposed modified symmetric
teleparallel gravity, in which gravitational Lagrangian is given by an
arbitrary function of non-metricity scalar . We have considered the
CDM jerk parameter to express the Hubble rate. Moreover, we have used
57 points of Hubble and 1048 points of Pantheon datasets to
constraint our model parameters by means of the Markov Chain Monte Carlo
analysis. The mean values and the best fit obtained give consistent Hubble rate
and deceleration parameter compared to the observation values. In order to
study the current accelerated expansion scenario of the Universe with the
presence of the cosmological fluid as a perfect fluid, we have considered two
forms of teleparallel gravity. We have studied the obtained field equations
with the proposed forms of models, specifically, linear and non-linear models.
Next, we have discussed the physical behavior of cosmological parameters such
as energy density, pressure, EoS parameter, and deceleration parameter for both
model. To ensure the validity of our proposed cosmological models, we have
checked all energy conditions. The properties of these parameters confirm that
our models describe the current acceleration of the expansion of the Universe.
This result is also corroborated by the energy conditions criteria. the
Finally, the EoS parameter for both models indicates that the cosmological
fluid behaves like a quintessence dark energy model.Comment: 12 pages, 10 figure
Parabolic groups acting on one-dimensional compact spaces
Given a class of compact spaces, we ask which groups can be maximal parabolic
subgroups of a relatively hyperbolic group whose boundary is in the class. We
investigate the class of 1-dimensional connected boundaries. We get that any
non-torsion infinite f.g. group is a maximal parabolic subgroup of some
relatively hyperbolic group with connected one-dimensional boundary without
global cut point. For boundaries homeomorphic to a Sierpinski carpet or a
2-sphere, the only maximal parabolic subgroups allowed are virtual surface
groups (hyperbolic, or virtually ).Comment: 10 pages. Added a precision on local connectedness for Lemma 2.3,
thanks to B. Bowditc
Kabylie : Géographie
« KABYLIE » (E.B.) La Kabylie, principale région berbérophone d’Algérie, occupe une place très particulière dans l’ensemble du monde berbère contemporain ; cette situation justifie une attention particulière, avec un dossier considérable qui rassemble 18 notices – et qui bien sûr est loin d’être exhaustif ! Le poids démographique de la Kabylie, son rôle dans l’histoire récente de l’Algérie, l’importance et le dynamisme de ses élites de tous types, son rôle décisif dans l’émergence de la consc..
Typologie et dynamique des chênaies vertes en Algérie
Le chêne vert figure parmi les essences forestières les plus importantes de la région méditerranéenne. L'état actuel de ses peuplements en Algérie, la régression de son aire, son importance écologique et la nécessité, dans le contexte mondial actuel, de promouvoir la conservation de la biodiversité et le développement durable des écosystèmes sont autant d'éléments qui nous ont amenés à envisager l'élaboration d'une typologie des chênaies vertes en Algérie, qui constituerait la première étape préalable à toute stratégie de gestion. L'importance du territoire étudié, a permis d'analyser et d'évaluer, à différentes échelles, la diversité de la chênaie verte en relation avec celle des milieux climatique et édaphique, et d'appréhender les conséquences d'un dérèglement fonctionnel sur les caractéristiques biologiques et phytogéographiques des phytocénoses (communautés végétales) ainsi que sur les propriétés trophiques (nutritives) et hydriques du sol
Kabylie : Géographie
« KABYLIE » (E.B.) La Kabylie, principale région berbérophone d’Algérie, occupe une place très particulière dans l’ensemble du monde berbère contemporain ; cette situation justifie une attention particulière, avec un dossier considérable qui rassemble 18 notices – et qui bien sûr est loin d’être exhaustif ! Le poids démographique de la Kabylie, son rôle dans l’histoire récente de l’Algérie, l’importance et le dynamisme de ses élites de tous types, son rôle décisif dans l’émergence de la consc..
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