# Examples of HNN-extensions with nontrivial quasi-kernels

 Title Examples of HNN-extensions with nontrivial quasi-kernels Publication Type Journal Article Year of Publication 2020 Authors Ivanov NA Journal Annuaire de l’Université de Sofia “St. Kliment Ohridski”. Faculté de Mathématiques et Informatique Volume 107 Start Page 107 Pagination 107-129 ISSN 1313-9215 (Print) 2603-5529 (Online) Keywords $C^*$-simplicity, HNN-extensions, inner amenability Abstract We introduce some examples of HNN-extensions motivated by the problems of $C^*$-simplicity and unique trace property. Moreover, we prove that our examples are not inner amenable and identify a relatively large, simple, normal subgroup in each one.
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