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Null productions

 

Null productions tex2html_wrap_inline8453 introduce some complications into the relatively straightforward parser operation described so far, some of which are due specifically to the probabilistic aspects of parsing. This section summarizes the necessary modifications to process null productions correctly, using the previous description as a baseline. Our treatment of null productions follows the (non-probabilistic) formulation of Graham:80, rather than the original one in Earley:70.





Andreas Stolcke
Sat Jun 29 21:49:02 PDT 1996