Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userLower bounds on the maximum dimension of a simple module in characteristic p
80
0
0.0
(
0
)
Authors
Geoffrey R. Robinson
Ask ChatGPT about the research
No Arabic abstract
We obtain lower bounds for the maximum dimension of a simple FG-module, where G is a finite group and F is an algebraically closed field of characteristic p. The bounds are described in terms of properties of p-subgroups of G. When p is 2 or p is a Mersenne prime, the bounds take a different form, due to exceptions which arise for such primes.
rate research
Read More
We give a short proof of the fact that if all characteristic p simple modules of the finite group G have dimension less than p, then G has a normal Sylow p-subgroup.
In this paper we measure how efficiently a finite simple group $G$ is generated by its elements of order $p$, where $p$ is a fixed prime. This measure, known as the $p$-width of $G$, is the minimal $kin mathbb{N}$ such that any $gin G$ can be written as a product of at most $k$ elements of order $p$. Using primarily character theoretic methods, we sharply bound the $p$-width of some low rank families of Lie type groups, as well as the simple alternating and sporadic groups.
For each $n$ we construct examples of finitely presented $C(1/6)$ small cancellation groups that do not act properly on any $n$-dimensional CAT(0) cube complex.
In 1878, Jordan proved that if a finite group $G$ has a faithful representation of dimension $n$ over $mathbb{C}$, then $G$ has a normal abelian subgroup with index bounded above by a function of $n$. The same result fails if one replaces $mathbb{C}$ by a field of positive characteristic, due to the presence of large unipotent and/or Lie type subgroups. For this reason, a long-standing problem in group and representation theory has been to find the correct analogue of Jordans theorem in characteristic $p>0$. Progress has been made in a number of different directions, most notably by Brauer and Feit in 1966; by Collins in 2008; and by Larsen and Pink in 2011. With a 1968 theorem of Steinberg in mind (which shows that a significant proportion of elements in a simple group of Lie type are unipotent), we prove in this paper that if a finite group $G$ has a faithful representation over a field of characteristic $p$, then a significant proportion of the elements of $G$ must have $p$-power order. We prove similar results for permutation groups, and present a general method for counting $p$-elements in finite groups. All of our results are best possible.
Fix an arbitrary finite group $A$ of order $a$, and let $X(n,q)$ denote the set of homomorphisms from $A$ to the finite general linear group ${rm GL}_n(q)$. The size of $X(n,q)$ is a polynomial in $q$. In this note it is shown that generically this polynomial has degree $n^2(1-a^{-1}) - epsilon_r$ and leading coefficient $m_r$, where $epsilon_r$ and $m_r$ are constants depending only on $r := n mod a$. We also present an algorithm for explicitly determining these constants.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
