Limit groups and automorphisms of κ-existentially closed groups

2025-03-15
Kaya, Burak
Kuzucuoğlu, Mahmut
Longobardi, Patrizia
Maj, Mercede
The structure of automorphism groups of κ-existentially closed groups has been studied by Kaya-Kuzucuoğlu in 2022. It was proved that Aut(G) is the union of subgroups of level preserving automorphisms and |Aut(G)|=2κ whenever κ is an inaccessible cardinal and G is the unique κ-existentially closed group of cardinality κ. The cardinality of the automorphism group of a κ-existentially closed group of cardinality λ>κ is asked in Kourovka Notebook Question 20.40. Here we answer positively the promised case κ=λ namely: If G is a κ-existentially closed group of cardinality κ, then |Aut(G)|=2κ. We also answer Kegel's question on universal groups, namely: For any uncountable cardinal κ, there exist universal groups of cardinality κ.
Journal of Algebra
Citation Formats
B. Kaya, M. Kuzucuoğlu, P. Longobardi, and M. Maj, “Limit groups and automorphisms of κ-existentially closed groups,” Journal of Algebra, vol. 666, pp. 840–849, 2025, Accessed: 00, 2025. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85212544589&origin=inward.