Constructive Learning of Context-Free Languages with a Subpansive Tree

A subpansive tree is a rooted tree that gives a partial order of nonterminal symbols of a context-free grammar. We formalize subpansive trees as background knowledge of CFGs, and investigate query learning of CFGs with the help of subpansive trees. We show a restricted class of CFGs, which we call hierarchical CFGs, is efficiently learnable, while it is unlikely to be polynomial-time predictable.

• Type: Conference
• Year: 2000
• Where: ICGI
• Authors: Noriko Sugimoto, Takashi Toyoshima, Shinichi Shimozono, Kouichi Hirata
• Keywords: Context-free Grammar, ICGI 2000, Natural Language Processing, Rooted Tree, Subpansive Trees