Test elements, retracts and automorphic orbits

被引:10
作者
Gong, Sheng-Jun [1 ]
Yu, Jie-Tai [1 ]
机构
[1] Univ Hong Kong, Dept Math, Hong Kong, Hong Kong, Peoples R China
关键词
test element; retract; automorphic orbit; free associative algebra; degree estimate; polynomial algebra; coordinate;
D O I
10.1016/j.jalgebra.2008.07.012
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Let A(2) be a free associative or polynomial algebra of rank two over a field K of characteristic zero. Based on the degree estimate of Makar-Limanov and J.-T. Yu, we prove: (1) An element p is an element of A(2) is a test element if p does not belong to any proper retract of A(2); (2) Every endomorphism preserving the automorphic orbit of a nonconstant element of A(2) is an automorphism. (c) 2008 Elsevier Inc. All rights reserved.
引用
收藏
页码:3062 / 3068
页数:7
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