1. Department of Mathematics and Informatics, University of Novi Sad, Novi Sad, Republic of Serbia https://people.dmi.uns.ac.rs/~borisha
2. Department of Mathematics, National University of Singapore, Republic of Singapore 119076 https://dilip-raghavan.github.io/
3. Department of Logic, Faculty of Arts, Charles University, Prague, Czech Republic https://jonathan.temno.eu/