Here's the entry on steps: http://www.w3.org/TR/xquery-semantics/#id-axis-steps
I missed it before. To be continued I guess. I'd love the idea of a sound formal proof. Op dinsdag 26 januari 2016 heeft W.S. Hager <[email protected]> het volgende geschreven: > Hi Adam, > > I'm looking at the formal specification of xpath/xquery: > > http://www.w3.org/TR/xquery-semantics > > It would really help to start with a function that implements the actual > selection in steps. Do you know such a function? > > Thanks, > > Wouter > Op dinsdag 26 januari 2016 heeft W.S. Hager <[email protected] > <javascript:_e(%7B%7D,'cvml','[email protected]');>> het volgende > geschreven: > >> Not really, no. But my guess is that the path is not relevant, as its >> steps simply contain variable names. The proof you want to have is a formal >> one, and I think it doesn't have to do with the path expression, but rather >> the formalism it implements. >> >> 2016-01-26 17:41 GMT+01:00 Adam Retter <[email protected]>: >> >>> Any chance you could offer me an example? ;-) >>> >>> On 26 January 2016 at 16:40, W.S. Hager <[email protected]> wrote: >>> > Hi Adam, >>> > >>> > Perhaps it helps to start with rewriting the xpath expressions as pure >>> > lambda expressions. Maybe that way you could apply lambda calculus? >>> > >>> > Cheers, >>> > Wouter >>> > >>> > 2016-01-26 17:26 GMT+01:00 Adam Retter <[email protected]>: >>> >> >>> >> Given two simple XPaths, say: >>> >> >>> >> 1. //w >>> >> >>> >> 2. /x/y/z/w[@a = 'v'] >>> >> >>> >> As a human I can very easily tell without evaluating the expressions >>> >> that (2) will return a subset (or the same set) of the results that >>> >> (1) would return *should* they both be evaluated. >>> >> >>> >> My goal here is given any two simple arbitrary XPaths expressed as >>> >> strings, and without evaluating them against a context, to determine >>> >> whether one would return a subset of the results of the other. >>> >> >>> >> I wondered if there might be an algorithm or library that someone >>> >> already had or has written which might be able to give me the answer? >>> >> >>> >> I realise that I can only probably cover a subset of XPath itself, but >>> >> it is only the path steps with predicates which I am interested in. >>> >> >>> >> Ideally I am looking for something in Java. >>> >> >>> >> -- >>> >> Adam Retter >>> >> >>> >> skype: adam.retter >>> >> tweet: adamretter >>> >> http://www.adamretter.org.uk >>> >> _______________________________________________ >>> >> [email protected] >>> >> http://x-query.com/mailman/listinfo/talk >>> > >>> > >>> > >>> > >>> > -- >>> > >>> > W.S. Hager >>> > Lagua Web Solutions >>> > http://lagua.nl >>> >>> >>> >>> -- >>> Adam Retter >>> >>> skype: adam.retter >>> tweet: adamretter >>> http://www.adamretter.org.uk >>> >> >> >> >> -- >> >> W.S. Hager >> Lagua Web Solutions >> http://lagua.nl >> > > > -- > > W.S. Hager > Lagua Web Solutions > http://lagua.nl > > -- W.S. Hager Lagua Web Solutions http://lagua.nl
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