Zhe Chen 0011 Yunyun Chen Robert M. Hierons Yifan Wu Four-Valued Monitorability of ømega-Regular Languages. 198-214 2020 ICFEM https://doi.org/10.1007/978-3-030-63406-3_12 conf/icfem/2020 db/conf/icfem/icfem2020.html#ChenCHW20