When different norms lead to same billiard trajectories?
A. Akopyan, R. Karasev, European Journal of Mathematics 8 (2022) 1309–1312.
LibreCat: https://research-explorer.ista.ac.at/record/7791
DOI: 10.1007/s40879-020-00405-0
arXiv: 1912.12685

Coarse infinite-dimensionality of hyperspaces of finite subsets
T. Weighill, T. Yamauchi, N. Zava, European Journal of Mathematics (2021).
LibreCat: https://research-explorer.ista.ac.at/record/10608
DOI: 10.1007/s40879-021-00515-3

Billiards in ellipses revisited
A. Akopyan, R. Schwartz, S. Tabachnikov, European Journal of Mathematics (2020).
LibreCat: https://research-explorer.ista.ac.at/record/8538
DOI: 10.1007/s40879-020-00426-9
arXiv: 2001.02934

Tropical formulae for summation over a part of SL(2,Z)
N. Kalinin, M. Shkolnikov, European Journal of Mathematics 5 (2019) 909–928.
LibreCat: https://research-explorer.ista.ac.at/record/441
DOI: 10.1007/s40879-018-0218-0
arXiv: 1711.02089