Alka Choubey - Mathematics Department, Jaypee Institute of Information Technol- ogy, A-۱۰, Sector-۶۲, Noida-۲۰۱۳۰۷ (U. P.), India
K. M. Ravi - Department of Mathematics, JSS Academy of Technical Education, C- ۲۰/۱, Sector-۶۲, Noida-۲۰۱۳۰۱ (U. P), India

Intuitionistic fuzzy regular language, Interval-valued fuzzy regular language, Vague regular language, Finite automaton with vague (final) states, Finite automaton with intuitionistic fuzzy (nal) states, Myhill-Nerode theorem