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A problem of Hanna Neumann on closed sets of group words
Published online by Cambridge University Press: 17 April 2009
Abstract
In Problem 1 of her book Varieties of groups, Hanna Neumann asked whether a fully invariant subsemigroup of a free group of infinite rank is necessarily a subgroup. This note presents an example which shows that the answer is negative.
- Type
- Research Article
- Information
- Bulletin of the Australian Mathematical Society , Volume 5 , Issue 3 , December 1971 , pp. 341 - 342
- Copyright
- Copyright © Australian Mathematical Society 1971
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