[xquery-talk] Function for determining one XPath as subset of another

W.S. Hager wshager at gmail.com
Wed Jan 27 01:12:36 PST 2016


I think simplifying notions of path expressions aren't necessary. IMO the
challenge here is to come to discreet formal steps. I'd start with applying
all normalisations in http://www.w3.org/TR/xquery-semantics/#id-axis-steps,
from which a single evaluable function could be derived. The function
should be rewritable as yielding the same set (for /x/w and //w). Next the
relation to the subset should become obvious.


Op woensdag 27 januari 2016 heeft Michael Kay <mike at saxonica.com
<javascript:_e(%7B%7D,'cvml','mike at saxonica.com');>> het volgende
geschreven:

>
> >
> >
> > If you want to do a formal proof, you might want to use simplified
> notions of XML documents and path expressions.
>
> It seems to be a long-standing tradition that computer scientists, when
> asked to prove a difficult conjecture C, respond by giving a proof for a
> simplified conjecture C'. While this might lead to progress in the long
> run, and enables them to get papers published in the academic literature,
> it is totally useless to practical engineeers who want to know whether they
> can safely rely on C.
>
> Michael Kay
> Saxonica
>
>
>
>

-- 

W.S. Hager
Lagua Web Solutions
http://lagua.nl
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