RE: Grammar Specification Question

Any parsing text will tell you that not all recursions are troublesome. In
most cases, only left recursion requires much more effort to be handled. If
you look around in the this industry. Not every vendor handles left
recursive grammar. 


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From: www-voice-request@w3.org [mailto:www-voice-request@w3.org] On Behalf
Of Cassandra Guy
Sent: Monday, June 21, 2004 12:43 PM
To: www-voice@w3.org
Subject: Grammar Specification Question


When I was reading the speech grammar specification located at:
http://www.w3.org/TR/grammar-spec/
 
I read the comment on recursion stated as follows:

The Speech Recognition Grammar Specification has the expressive power of a
Context Free Grammar. This arises because the language permits a rule to
directly or indirectly reference itself. [Note: a Conforming XML Form
<http://www.w3.org/TR/grammar-spec/#S5.4> Grammar Processor or Conforming
ABNF Form Grammar Processor <http://www.w3.org/TR/grammar-spec/#S5.6>  is
not required to support recursive grammars.]

Why is recursion not required for a grammar processor to conform? Is this a
difficult feature to add? Do some processors support this feature already?
Any information that can be provided on this decision would be extremely
helpful for my development project. Thank you in advance.

-Cassandra Guy



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