Abstract
MSC: 26A51, 26D07, 49K35 DOI: 10.21538/0134-4889-2023-29-4-193-216 This research of Béla Nagy was supported by project TKP2021-NVA-09. Project no. TKP2021-NVA-09 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NVA funding scheme. The