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Re: Non-deterministic content model
- From: Eric Bohlman <email@example.com>
- To: Marcus Carr <firstname.lastname@example.org>, Jason Chalecki <email@example.com>
- Date: Wed, 13 Jun 2001 21:43:56 -0500
6/13/01 6:05:25 PM, Marcus Carr <firstname.lastname@example.org> wrote:
>Jason Chalecki wrote:
>> ((a, b)*, a) essentially represents the language where the first and
>> last letter is a. Additionally, if there are b's, a and b must
>> alternate. So (a, (b, a)*) matches the same language and is
>> deterministic, correct?
>Yes, but the original model was allowed to finish with either a or b - the
>final a had a question mark. To model that with your approach would result
>in (a, (b, a?)*), which allows a string of b's with no intervening a's.
>Either way, you've changed the model.
Applying the subset construction to the NFA associated with the original model ((a, b)*, a?), I end
up with a two-state DFA in which both states are final:
0 1 -
1 - 0
but I can't figure out how to express it as a content model (or regular expression).