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[Bug 20632] New: [XP 3.0] Transitivity of subtype relationships

From: <bugzilla@jessica.w3.org>
Date: Thu, 10 Jan 2013 12:33:59 +0000
To: public-qt-comments@w3.org
Message-ID: <bug-20632-523@http.www.w3.org/Bugs/Public/>

            Bug ID: 20632
           Summary: [XP 3.0] Transitivity of subtype relationships
    Classification: Unclassified
           Product: XPath / XQuery / XSLT
           Version: Last Call drafts
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: XPath 3.0
          Assignee: jonathan.robie@gmail.com
          Reporter: mike@saxonica.com
        QA Contact: public-qt-comments@w3.org

I think we would all agree that there is a fundamental principle that subtyping
relationships need to be transitive: A<:B and B<:C implies A<:C. Sadly this is
not currently true of the subtyping rules for union types.

According to the current rules, subtype(xs:decimal, union(xs:decimal,
xs:string)) is true, and subtype(xs:integer, xs:decimal) is true, but
subtype(xs:integer, union(xs:decimal, xs:string)) is false.

This is clearly an oversight and should be fixed.

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Received on Thursday, 10 January 2013 12:34:00 UTC

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