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- From: "Rick Jelliffe" <ricko@allette.com.au>
- To: <xml-dev@ic.ac.uk>
- Date: Sat, 4 Dec 1999 17:35:33 +0800
Murata Makoto of FujiXerox has been working on the question of set
operations on grammars for several years.
Rick Jelliffe
-----Original Message-----
From: Martin Bryan <mtbryan@sgml.u-net.com>
To: xml-dev@ic.ac.uk <xml-dev@ic.ac.uk>
Date: Saturday, 4 December 1999 16:24
Subject: Problem for mathematically minded XML experts
>I would like to pose the following question to those of you with a
>mathematical bent who have some spare time (I'm not expecting the
answer
>quickly - this is a holiday teaser I suspect!).
>
>Given I have two DTDs, in which there are two elements whose models can
be
>described as follows:
>
>Element DTD1 consists of a sequence of E1 elements and G1 OR groups,
where
>the total number of elements in the OR groups is N1
>
>and
>
>Element DTD2 consists of a sequence of E2 elements and G2 OR groups,
where
>the total number of elements in the OR groups is N2
>
>is there a formula that can be used to determine whether the same pair
of
>elements are valid in both DTD1 and DTD2? If there is, is there a way
to
>determine the difference caused by the following conditions being
added:
>
>a) there need be no constraint on the order of the elements
>b) the elements must be in a particular order
>c) the elements must be adjacent, in any order
>d) the elements must be adjacent, in a particular order.
>
>Does the split of the number of elements in each OR group affect the
>calculation significantly?
>Does the fact that one or other, or both of the elements is a member of
a
>group significantly affect the calculation?
>How would the calculation change if it was required that three matches
were
>required from the model?
>
>If you can help me understand any part of the problem, or point me to a
>paper/book on the subject, I would be grateful.
>
>Martin Bryan, 29 Oldbury Orchard, Churchdown, Glos GL3 2PU, UK
>Phone/Fax: +44 1452 714029 E-mail: mtbryan@sgml.u-net.com
>
>
>
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