A Sufficient Condition for Learning Unbounded Unions of Languages with Refinement Operators. - Tomohiko Okayama; Ryo Yoshinaka; Keisuke Otaki; Akihiro Yamamoto (ISAIM, 2014)

Learning concepts and their unions from positive data with refinement operators. - Seishi Ouchi; Tomohiko Okayama; Keisuke Otaki; Ryo Yoshinaka; Akihiro Yamamoto (Ann. Math. Artif. Intell., 2017)