Re: XQuery (and XML) vs LISP
From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Tue, 07 Feb 2006 22:51:02 GMT
Message-ID: <qv9Gf.242146$6M5.7676981_at_phobos.telenet-ops.be>
>>I think the answer is, vaguely, yes. :-) You can think of the tree is a
>>binary relation, and if you want access to all descendants the system
>>could provide conceptually the transitive closure to you (so for the
>>binary table R you could for example use R* as the notation for its
>>transitive closure) and from there you could specify your queries as
>>usual. Most XPath queries would then translatie to simple
>>SELECT-FROM-WHERE queres.
Date: Tue, 07 Feb 2006 22:51:02 GMT
Message-ID: <qv9Gf.242146$6M5.7676981_at_phobos.telenet-ops.be>
dawn wrote:
> Jan Hidders wrote: >
>>I think the answer is, vaguely, yes. :-) You can think of the tree is a
>>binary relation, and if you want access to all descendants the system
>>could provide conceptually the transitive closure to you (so for the
>>binary table R you could for example use R* as the notation for its
>>transitive closure) and from there you could specify your queries as
>>usual. Most XPath queries would then translatie to simple
>>SELECT-FROM-WHERE queres.
> > If they are not nested relations but nested ordered lists, as possible > with XML documents, then you would lose information this way, right?
Right. But you could add an extra binary relation that defines the order.
- Jan Hidders