I haven't looked at ORO's implementation, but typically regexps get
'compiled' into a state-machine, which is basically a directect graph.
Some graph theory (along with some regexp-specific domain knowledge)
should be able to do some analysis.
-bob
On Tue, 26 Mar 2002, Vollmer, Thomas - CannonSA wrote:
> Gunther,
>
> I will face a similar problem in the near future and would
> be very interested what you and others find out about this
> problem. I haven't looked at possible approaches myself yet,
> as the issue isn't a pressing one at the moment. I am not a
> regex expert but I have the feeling that this could be a
> though one. If it is feasible though, I would of course be
> all for adding it to ORO :-)
>
> Best regards,
> Thomas
>
>
> > -----Original Message-----
> > From: Gunther Schadow [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, March 25, 2002 4:12 PM
> > To: oro-user
> > Subject: Comparing two Regex *Patterns*
> >
> >
> > Hi,
> >
> > for an XSLT-based up-translation engine that I'm writing, I
> > am using ORO matcher. Works very well (and better than the
> > other two options), thanks!
> >
> > Now I wonder about the following and wanted some input from
> > experts on theory of regular expressions and their compilers
> > and matchers: is there some algebraic way of comparing two
> > regex patterns (not a string with a pattern, but two patterns.)
> > The point is to figure out if one pattern is (partially)
> > contained in another pattern and if strings matched by one
> > pattern are also matched by another pattern (i.e. the set
> > of strings mathing pattern 2 is a subset of the set of
> > strings matching pattern 1.) The use case for this is to
> > find ambiguities between rules using such related patterns
> > such that one can test these patterns in groups (or, for
> > XSLT, assign higher priority to the more specific pattern.)
> > The point is that the computer should make this analysis
> > not the guy who defines a transformation using many regexes.
> >
> > Generally evaluating such similarity relationships could be
> > fairly involved. But I think this question should be part of
> > any theoretical discussion of regexes, and if anyone knows
> > of some information about this please holler. Actually I am
> > just now searching through the Annals of the ACM and there
> > are a few pertinent articles that feel like this is a hard
> > problem. Anyone knows of any implementations of any of this?
> > Do people here feel that comparison operations between Patterns
> > would be a good addition to ORO (if it is feasible)?
> >
> > thanks,
> > -Gunther Schadow
> >
> > PS: I would appreciate if you could put my personal email
> > address on your replies. Thanks.
> >
> >
> >
> > --
> > Gunther Schadow, M.D., Ph.D.
> > [EMAIL PROTECTED]
> > Medical Information Scientist Regenstrief Institute for
> > Health Care
> > Adjunct Assistant Professor Indiana University School
> > of Medicine
> > tel:1(317)630-7960
> > http://aurora.regenstrief.org
> >
> >
> >
> > --
> > To unsubscribe, e-mail:
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> > For additional commands, e-mail:
> > <mailto:[EMAIL PROTECTED]>
> >
>
>
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