[Bug 5886] New: distance formal semantics is inconsistent with example

http://www.w3.org/Bugs/Public/show_bug.cgi?id=5886

           Summary: distance formal semantics is inconsistent with example
           Product: XPath / XQuery / XSLT
           Version: Candidate Recommendation
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Full Text 1.0
        AssignedTo: jim.melton@acm.org
        ReportedBy: zhen.liu@oracle.com
         QAContact: public-qt-comments@w3.org


in http://www.w3.org/TR/xpath-full-text-10/#ftdistance, we have 2nd example:

The following expression returns false:

/books/book ftcontains "web" ftand "site" ftand
"usability" distance at most 2 words

The search context does contain the phrase "The usability of a Web site", in
which the tokens "usability" and "Web" have a distance of 2 words, and the
tokens "Web" and "site" have a distance of 0 words, both of which satisfy the
constraint distance at most 2 words. However, the problem is that "usability"
and "site" have a distance of 3 words, which does not satisfy the constraint,
and so the distance selection yields no matches, and the expression as a whole
yields false. (The phrase "Improving Web Site Usability" would satisfy the
given full-text selection, but it occurs in an attribute value, and so is not
subject to tokenization.)

This means the distance is applied to every pair of matching tokens.
However, in http://www.w3.org/TR/xpath-full-text-10/#tq-ft-fs-FTDistance, the
formal semantic xquery defintion, it applies distance predicate on matching
token sorted by their token postion.
Therefore, they are not compared in pairwise manner. For the above example,
only "usability" and "web" are compared ; "web" and "site" are compared, but 
"usability" and "site" are NOT compared, then the expression in the example
shall return true instead of false.


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Received on Monday, 21 July 2008 21:12:55 UTC