Efficient Learning of Context-Free Grammars from Positive Structural Examples

نویسنده

  • Yasubumi Sakakibara
چکیده

In this paper, we introduce a new normal form for context-free grammars, called reversible context-free grammars, for the problem of learning context-free grammars from positive-only examples. A context-free grammar G = (N, Z, P, S) is said to be reversible if (1) A + G( and B -+ a in P implies A = B and (2) A -+ a@ and A --f aCfl in P implies B = C. We show that the class of reversible context-free grammars can be identified in the limit from positive samples of structural descriptions and there exists an efficient algorithm to identify them from positive samples of structural descriptions, where a structural description of a context-free grammar is an unlabelled derivation tree of the grammar. This implies that if positive structural examples of a reversible context-free grammar for the target language are available to the learning algorithm, the full class of context-free languages can be learned efftciently from positive samples.

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عنوان ژورنال:
  • Inf. Comput.

دوره 97  شماره 

صفحات  -

تاریخ انتشار 1992