Horváth, Sándor, Efim Kinber, Arto Salomaa, and Sheng Yu. “Decision Problems Resulting from Grammatical Inference”. Annales Fennici Mathematici 12, no. 2 (August 1, 1987): 287–298. Accessed November 25, 2024. https://afm.journal.fi/article/view/134604.