Results 1 to 10 of about 1,123 (133)

Chains of modular elements and shellability [PDF]

, 2012
Let L be a lattice admitting a left-modular chain of length r, not necessarily maximal. We show that if either L is graded or the chain is modular, then the (r-2)-skeleton of L is vertex-decomposable (hence shellable).
Babson, Birkhoff, Björner, Björner, Björner, Brown, Duval, Forman, Hersh, Hersh, Jonsson, Jonsson, Kohler, Kozlov, Liu, McNamara, Provan, Russ Woodroofe, Sagan, Shareshian, Shareshian, Stanley, Stanley, Thomas, Thévenaz, Wachs, Wachs, Woodroofe, Woodroofe, Woodroofe   +29 more
core   +1 more source

Arrangements of ideal type

, 2017
In 2006 Sommers and Tymoczko defined so called arrangements of ideal type A_I stemming from ideals I in the set of positive roots of a reduced root system. They showed in a case by case argument that A_I is free if the root system is of classical type or
Roehrle, Gerhard
core   +1 more source

Antichain cutsets of strongly connected posets

, 2012
Rival and Zaguia showed that the antichain cutsets of a finite Boolean lattice are exactly the level sets. We show that a similar characterization of antichain cutsets holds for any strongly connected poset of locally finite height.
A Aramova, A Björner, A Björner, A Björner, A Björner, A Björner, A Björner, A Hatcher, G Behrendt, I Rival, I Rival, J Ginsburg, M Bell, M Stern, P McNamara, RP Stanley, RP Stanley, RP Stanley, RP Stanley, Russ Woodroofe, Stephan Foldes   +20 more
core   +1 more source

On the number of cyclic subgroups of a finite group

, 2018
Let $G$ be a finite group and let $c(G)$ be the number of cyclic subgroups of $G$. We study the function $\alpha(G) = c(G)/|G|$. We explore its basic properties and we point out a connection with the probability of commutation.
Garonzi, Martino, Lima, Igor
core   +1 more source

Lower central series and free resolutions of hyperplane arrangements

, 2002
If $M$ is the complement of a hyperplane arrangement, and $A=H^*(M,\k)$ is the cohomology ring of $M$ over a field of characteristic 0, then the ranks, $\phi_k$, of the lower central series quotients of $\pi_1(M)$ can be computed from the Betti numbers, $
Schenck, Henry K., Suciu, Alexander I.
core   +4 more sources

Evolving groups

, 2018
The class of evolving groups is defined and investigated, as well as their connections to examples in the field of Galois cohomology. Evolving groups are proved to be Sylow Tower groups in a rather strong sense.
Stanojkovski, Mima
core   +1 more source

$G$-permutable Subgroups in $\operatorname{PSL}_2(q)$ and Hereditarily $G$-permutable Subgroups in $\operatorname{PSU}_3(q)$

Известия Иркутского государственного университета: Серия "Математика"
The concept of $X$-permutable subgroup, introduced by A. N. Skiba, generalizes the classical concept of a permutable subgroup. Many classes of finite groups have been characterized in terms of $X$-permutable subgroups.
A. A. Galt, V. N. Tyutyanov
doaj   +1 more source

Finite group with some c#-normal and S-quasinormally embedded subgroups

Open Mathematics
Let pp be a prime that divides the order of a finite group GG, and let PP be a Sylow pp-subgroup of GG. Assume that dd is the smallest number of generators of PP and define ℳd(P)={P1,P2,…,Pd}{{\mathcal{ {\mathcal M} }}}_{d}\left(P)=\left\{{P}_{1},{P}_{2},
Li Ning, Jiang Jing, Liu Jianjun
doaj   +1 more source

Branes in Anti de Sitter Space-Time [PDF]

, 1998
An intense study of the relationship between certain quantum theories of gravity realized on curved backgrounds and suitable gauge theories, has been originated by a remarkable conjecture put forward by Maldacena almost one year ago.
Trigiante, M.
core   +2 more sources

SR-groups of Order 2ⁿp^m with Dihedral Sylow 2-subgroup

Моделирование и анализ информационных систем, 2007
The structure of SR-groups with dihedral Sylow 2-subgroup modulo Frattini subgroup is described. It is proved that if a group О is a non-supersolvable SR-group of order 2npm with dihedral Sylow 2-subgroup, p is Mersenne prime.
V. V. Yanishevskiy
doaj