Real-time logics: Complexity and expressiveness
R. Alur, T.A. Henzinger, Information and Computation 104 (1993) 35–77.
LibreCat: https://research-explorer.ista.ac.at/record/4589
DOI: 10.1006/inco.1993.1025

Minimum polygonal separation
H. Edelsbrunner, F. Preparata, Information and Computation 77 (1988) 218–232.
LibreCat: https://research-explorer.ista.ac.at/record/4090
DOI: 10.1016/0890-5401(88)90049-1