[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Converting a variety of data formats, containingvarious ki
Yeah, that makes sense, my wording is bad but that's why I qualified it with "reducible".... It sort of the same point you made about normalization and binary relational models: given enough triples you can relate anything to anything. However, to put your point another way, that doesn't mean that any given canonical triple model represents all the same metadata of another canonical triple model representing the same data... You can then, of course, create the triple model that is the intersection of these two models, ad infinitum. There are likely some group theory (or category theory) answers to what such models would look like when they are isopmorphic, but all your models have to form groups of the same size for my original statement to be true. Guess I'm spending too much time dreaming of a world where Odersky's Dotty (or similar) is the foundation for everything... Peter Hunsberger On Tue, Oct 4, 2016 at 2:14 PM, Michael Kay <mike@saxonica.com> wrote: >> >> Without giving this much thought; you could probably prove that all >> data modes that are "computationally tractable" are reducible to a >> model that is isomorphic to a triple store. > > Generally I don't think different data models are isomorphic except in trivial cases: you can't usually find a 1:1 mapping between their value spaces. If you try to find a function F that maps from the XML value space to the JSON value space, for example, you will typically find that if it's lossless (ie. represents every distinct XML value using a different JSON value, and therefore has an inverse F'), then it won't be the case that F' maps every distinct JSON value to a distinct XML value. > > Similarly if you map XML to a triple store, then the operation that reverses the mapping won't be useful as a general way of representing any triple store in XML. > > If such isomorphisms existed, it wouldn't be necessary to employ half the programming profession at any point in time devising conversions from format A to format B. > > Michael Kay > Saxonica
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