Re: XML Schema, 1-unambiguity, and XML Query
I have not checked it for quite some time. Efficiency is one issue, however 1-unambiguity gets in the way as such -- it is an open problem to obtain the strictest possible 1-unambiguous grammar given an operation and a 1-unambiguous grammer. If we allow 1-ambiguity, with or without ambiguity in interpretation (I hope you remember Makoto's talk at Extreme last year regarding interpretation - it is basically the same as type assignment), it becomes much easier. Anyways, I have not studied the claims of efficiency due to 1-unambiguity -- I will check them out some time. I have to do my homework. Also, we are talking about efficiency of schema operations -- and schema operations usually take a much smaller time when compared to the operations on the data. So does it really matter whether something is exponential or linear in the size of the schema?? regards - murali. On Wed, 20 Mar 2002, Jonathan Robie wrote: > At 12:06 PM 3/20/2002 -0800, Murali Mani wrote: > >The biggest problem with XML Schema spec as I see is the 1-unambiguity > >constraint -- this gets very badly in the way of XML Query, as I > >understand it. I wonder what others feel about it. > > Actually, 1-unambiguity has real advantages for efficient implementation of > structural subsumption. I don't think it particularly gets in the way of > XML Query. I used to think that it would. > > Jonathan >
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