[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Notable declarative expressions?
There's a grand unified theory of data modelling: Description Logics (the model theory underlying OWL2 aka the semantic web), which is about the best motivated theory there is for these kind of problems. Specifically, I guess you could model XSD grammar constraints using the description logic EL++ which, roughly speaking, admits expressing role inclusionship constraints as regular expressions over roles (and even a larger class of constraints; eg. consider papers by Yevgeny Kazakov), though to the best of my knowledge this hasn't been applied to XML model theory. But AFAIK the addition of general identity constraints (ID/IDREF) makes this logic undecidable. On 12/20/16, Michael Kay <mike@saxonica.com> wrote: > >> On 20 Dec 2016, at 17:57, Thomas Passin <list1@tompassin.net> wrote: >> >> I think you could (or at least I could) think of a schema as a model. > > I'm inclined to agree. It's at least as much a data model as the schema of a > relational database is. It defines a value space, and it provides mechanisms > for documenting the relationships between values in the value space and > things in the world outside. What else does it have to be to make it a data > model? > > The fact that XSDs primary mechanism for constraining the value space is by > means of a grammar is a distinguishing feature, but I don't see anything in > the theory of data modelling that says "the constraints on the value space > must be defined using mechanisms other than grammars". > > Michael Kay > Saxonica > _______________________________________________________________________ > > XML-DEV is a publicly archived, unmoderated list hosted by OASIS > to support XML implementation and development. To minimize > spam in the archives, you must subscribe before posting. > > [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ > Or unsubscribe: xml-dev-unsubscribe@lists.xml.org > subscribe: xml-dev-subscribe@lists.xml.org > List archive: http://lists.xml.org/archives/xml-dev/ > List Guidelines: http://www.oasis-open.org/maillists/guidelines.php >
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