Comparing the Ambiguity Reduction Abilities of Probabilistic Context-Free Grammars

نویسندگان

  • Gabriel G. Infante López
  • Maarten de Rijke
چکیده

We present a measure for evaluating Probabilistic Context Free Grammars (PCFG) based on their ambiguity resolution capabilities. Probabilities in a PCFG can be seen as a filtering mechanism: For an ambiguous sentence, the trees bearing maximum probability are single out, while all others are discarded. The level of ambiguity is related to the size of the singled out set of trees. Under our measure, a grammar is better than other if the first one has reduced the level of ambiguity in a higher degree. The measure we present is computed over a finite sample set of sentence because, as we show, it can not be computed over the set of sentences accepted by the grammar.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Studying impressive parameters on the performance of Persian probabilistic context free grammar parser

In linguistics, a tree bank is a parsed text corpus that annotates syntactic or semantic sentence structure. The exploitation of tree bank data has been important ever since the first large-scale tree bank, The Penn Treebank, was published. However, although originating in computational linguistics, the value of tree bank is becoming more widely appreciated in linguistics research as a whole. F...

متن کامل

On the Computation of Distances for Probabilistic Context-Free Grammars

Probabilistic context-free grammars (PCFGs) are used to define distributions over strings, and are powerful modelling tools in a number of areas, including natural language processing, software engineering, model checking, bio-informatics, and pattern recognition. A common important question is that of comparing the distributions generated or modelled by these grammars: this is done through che...

متن کامل

Extending Parikh's Theorem to Weighted and Probabilistic Context-Free Grammars

We prove an analog of Parikh’s theorem for weighted context-free grammars over commutative, idempotent semirings, and exhibit a stochastic context-free grammar with behavior that cannot be realized by any stochastic right-linear context-free grammar. Finally, we show that every unary stochastic context-free grammar with polynomially-bounded ambiguity has an equivalent stochastic right-linear co...

متن کامل

Parikh’s Theorem for Weighted and Probabilistic Context-Free Grammars

We prove an analog of Parikh’s theorem for weighted context-free grammars over commutative, idempotent semirings, and exhibit a stochastic context-free grammar with behavior that cannot be realized by any stochastic right-linear context-free grammar. Finally, we show that every unary stochastic context-free grammar with polynomially-bounded ambiguity has an equivalent stochastic right-linear co...

متن کامل

On the Ability of a Probabilistic Context-Free Grammar for Reducing Ambiguity

This paper studies the ambiguity reduction ability of the probabilistic contextfree grammar. We theoretically analyze the common behavior of any probabilistic context-free grammar. Moreover, we con rm by experiments that a probabilistic context-free grammar learnt from Japanese corpus has the ambiguity reduction ability as expected by the theoretical analysis.

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2004