Hopfian And Co-Hopfian Subsemigroups And Extensions
نویسندگان
چکیده
منابع مشابه
Hopfian and co-hopfian subsemigroups and extensions
This paper investigates the preservation of hopficity and co-hopficity on passing to finite-index subsemigroups and extensions. It was already known that hopficity is not preserved on passing to finite Rees index subsemigroups, even in the finitely generated case. We give a stronger example to show that it is not preserved even in the finitely presented case. It was also known that hopficity is...
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ژورنال
عنوان ژورنال: Demonstratio Mathematica
سال: 2014
ISSN: 2391-4661,0420-1213
DOI: 10.2478/dema-2014-0064