Let n be an integer greater than 1. A group G is said to be n-permutable whenever for every n-tuple x 1 x n of elements of G there exists a non-identity permutation ฯ of 1 In this paper we prove that an infinite group G is n-permutable if and only if for every n infinite subsets X 1 X n of G there
Orbits onn-tuples for Infinite Permutation Groups
โ Scribed by Francesca Merola
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 183 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0195-6698
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โฆ Synopsis
This paper presents a theorem on the growth rate of the orbit-counting sequences of a primitive oligomorphic group: if G is not a highly homogeneous group, then the growth rate for the sequence counting orbits on n-tuples of distinct elements is bounded below by c n n!, where c โ 1.172.
The previously known lower bounds concerned all not highly transitive groups, including highly homogeneous groups which are known to have roughly factorial growth rate. This paper shows that highly homogeneous groups are the only groups with such a growth rate, while for all other primitive groups the growth rate is faster and the bound is improved by an exponential factor.
๐ SIMILAR VOLUMES
Suppose that โ is an infinite set and k is a natural number. Let โ denote the set of all k-subsets of โ and let F be a field. In this paper we study the ลฝ . w x k FSym โ -submodule structure of the permutation module F โ . Using the representation theory of finite symmetric groups, we show that ever