Search results for "Group theory"
showing 10 items of 703 documents
Word classes and the scope of lexical flexibility in Tongan
2017
Abstract Tongan is an Oceanic language belonging to the Polynesian subgroup. Based on previous work (Churchward 1953, Tchekhoff 1981, Broschart 1997), Tongan has been classified as a 'flexible' language by various typological approaches on word classes (Hengeveld 1992, Rijkhoff 1998, Croft 2001). This means that lexical items are per se not categorised in terms of major word classes, but they can function as noun, verb, adjective and manner adverb without morphosyntactic derivation. However, not all lexemes are entirely flexible occurring within all these constructions. So the crucial issue of how flexible Tongan really is remains. This question will be addressed by a survey based on a comb…
Lie Algebras Generated by Extremal Elements
1999
We study Lie algebras generated by extremal elements (i.e., elements spanning inner ideals of L) over a field of characteristic distinct from 2. We prove that any Lie algebra generated by a finite number of extremal elements is finite dimensional. The minimal number of extremal generators for the Lie algebras of type An, Bn (n>2), Cn (n>1), Dn (n>3), En (n=6,7,8), F4 and G2 are shown to be n+1, n+1, 2n, n, 5, 5, and 4 in the respective cases. These results are related to group theoretic ones for the corresponding Chevalley groups.
On presentations for mapping class groups of orientable surfaces via Poincaré's Polyhedron theorem and graphs of groups
2021
The mapping class group of an orientable surface with one boundary component, S, is isomorphic to a subgroup of the automorphism group of the fundamental group of S. We call these subgroups algebraic mapping class groups. An algebraic mapping class group acts on a space called ordered Auter space. We apply Poincaré's Polyhedron theorem to this action. We describe a decomposition of ordered Auter space. From these results, we deduce that the algebraic mapping class group of S is a quotient of the fundamental group of a graph of groups with, at most, two vertices and, at most, six edges. Vertex and edge groups of our graph of groups are mapping class groups of orientable surfaces with one, tw…
The average element order and the number of conjugacy classes of finite groups
2021
Abstract Let o ( G ) be the average order of the elements of G, where G is a finite group. We show that there is no polynomial lower bound for o ( G ) in terms of o ( N ) , where N ⊴ G , even when G is a prime-power order group and N is abelian. This gives a negative answer to a question of A. Jaikin-Zapirain.
Machine $B_4$
2020
We construct map $\xi$. It exhibits dense orbits for all $x\in\overline{0,1}^\omega$. We give elementary proofs for all statements.
The proof of Birman’s conjecture on singular braid monoids
2003
Let B_n be the Artin braid group on n strings with standard generators sigma_1, ..., sigma_{n-1}, and let SB_n be the singular braid monoid with generators sigma_1^{+-1}, ..., sigma_{n-1}^{+-1}, tau_1, ..., tau_{n-1}. The desingularization map is the multiplicative homomorphism eta: SB_n --> Z[B_n] defined by eta(sigma_i^{+-1}) =_i^{+-1} and eta(tau_i) = sigma_i - sigma_i^{-1}, for 1 <= i <= n-1. The purpose of the present paper is to prove Birman's conjecture, namely, that the desingularization map eta is injective.
Estimates for the differences of positive linear operators and their derivatives
2019
The present paper deals with the estimate of the differences of certain positive linear operators and their derivatives. Oxur approach involves operators defined on bounded intervals, as Bernstein operators, Kantorovich operators, genuine Bernstein-Durrmeyer operators, and Durrmeyer operators with Jacobi weights. The estimates in quantitative form are given in terms of the first modulus of continuity. In order to analyze the theoretical results in the last section, we consider some numerical examples.
Regular orbits of actions of finite soluble groups. Applications
2019
A lo largo de esta tesis, todos los conjuntos, grupos, cuerpos y módulos considerados se suponen finitos. Consideremos un grupo G actuando sobre un conjunto no vacío Ω. Decimos que la órbita de un w ∈ Ω es regular si C G (w) = {g ∈ G : wg = w} = 1; en este caso, dicha órbita consta de |G| elementos. El estudio de órbitas regulares de grupos lineales, es decir, órbitas regulares de acciones de subgrupos de GL(V ), siendo V un espacio vectorial, es importante en el desarrollo de muchas ramas de la teoría de grupos, incluendo los grupos resolubles, teoría de representaciones y grupos de permutaciones. De hecho, la solución de algunos problemas importantes en el área como el problema k(GV ) ([2…
Some results on locally finite groups
2017
En esta tesis se presentan algunos resultados sobre p-nilpotencia y permutabilidad en grupos localmente finitos. Está estructurada en cinco capítulos. El primer capítulo, que tiene carácter introductorio: contiene definiciones y resultados conocidos que serán utilizados en los capítulos sucesivos. Por tratarse de resultados ya conocidos, se introducen con referencias y sin demostraciones. En el capítulo 2 se trata la p-nilpotencia en grupos hiperfinitos, donde p es un primo. Los resultados presentados se encuentran publicados en el siguiente artículo: Ballester-Bolinches, A.; Camp-Mora, S.; Spagnuolo, F., "On p-nilpotency of hyperfinite groups". Monatshefte f¨ur Mathematik, 176, no. 4, 497–…
On the arithmetic and geometry of binary Hamiltonian forms
2011
Given an indefinite binary quaternionic Hermitian form $f$ with coefficients in a maximal order of a definite quaternion algebra over $\mathbb Q$, we give a precise asymptotic equivalent to the number of nonequivalent representations, satisfying some congruence properties, of the rational integers with absolute value at most $s$ by $f$, as $s$ tends to $+\infty$. We compute the volumes of hyperbolic 5-manifolds constructed by quaternions using Eisenstein series. In the Appendix, V. Emery computes these volumes using Prasad's general formula. We use hyperbolic geometry in dimension 5 to describe the reduction theory of both definite and indefinite binary quaternionic Hermitian forms.