Undecidability Results of Modal Definability in Extended Modal Languages
Written by：网站编辑
Last updated：2022-10-14
Studies in Logic, Vol. 14, No. 6 (2021): 25–40 PII: 16743202(2021)06002516
Zhiguang Zhao
Abstract.
In the present paper, we apply the methodology in Balbiani and Tinchev(2016) to show that for the modal language with universal modality 
, tense language 
, hybrid languages 
, 
(@), Chagrova’s theorem holds that the modal/tense/hybrid definability of firstorder sentences with respect to certain classes of frames is undecidable, by using similar techniques as stable classes of Kripke frames.