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# On certain finite linear groups of prime degree

## Citation

Sibley, David Alan (1972) On certain finite linear groups of prime degree. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:06132016-162549466

## Abstract

In studying finite linear groups of fixed degree over the complex field, it is convenient to restrict attention to irreducible, unimodular, and quasiprimitive groups. If one assumes the degree to be an odd prime p, there is a natural division into cases, according to the order of a Sylow p-group of such a group. When the order is p4 or larger, all such groups are known (by W. Feit and J. Lindsey, independently).

THEOREM 1. Suppose G is a finite group with a faithful, irreducible, unimodular, and quasiprimitive complex representation of prime degree p ≥ 5. If a Sylow p-group P of G has order p3, then P is normal in G.

As is well known, Theorem 1 is false for p = 2 or 3. Combining Theorem 1 with known results, we have immediately the following conjecture of Feit.

THEOREM 2. Suppose G is a finite group with a faithful, irreducible, and unimodular complex representation of prime degree p ≥ 5. Then p2 does not divide the order of G/0p(G).

The following result, which is of independent interest, is used in the proof of Theorem 1.

THEOREM 3. Suppose G is a finite group with a Sylow p-group P of order larger than 3, which satisfies

CG(x) = P, for all x ≠ 1 in P.

If G has a faithful complex representation of degree less than (|P| - 1)2/3, then P is normal in G.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Mathematics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Mathematics
Thesis Availability:Public (worldwide access)
• Wales, David B.
Thesis Committee:
• Unknown, Unknown
Defense Date:3 April 1972
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
Ford FoundationUNSPECIFIED
CaltechUNSPECIFIED
Record Number:CaltechTHESIS:06132016-162549466
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06132016-162549466
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9874
Collection:CaltechTHESIS
Deposited By: Leslie Granillo
Deposited On:14 Jun 2016 15:21