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Re: Updated definitions

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Thu, 19 May 2005 12:34:50 +0100
Message-ID: <428C79DA.1040702@hp.com>
To: Dan Connolly <connolly@w3.org>
CC: www-archive@w3.org, Pat Hayes <phayes@ihmc.us>, "Eric Prud'hommeaux" <eric@w3.org>



Andy wrote ">" and ">>>"
Dan wrote ">>"
<snip/>

>>>A substitution is a function from a subset of the set of variables to
>>>the set of RDF terms, RDF-T.
>>>
>>>The result of replacing every v in a graph pattern P by S(v) is
>>>written S(P).
>>>
>>>We say that S is a solution of P if P matches G with substitution S.
>>>
>>>Definition: Basic Graph Pattern 
>>>
>>>A Basic Graph Pattern is a set of Triple Patterns.
>>>
>>>A basic graph pattern matches on graph G with substitution S if S(GP)
>>>is entailed by G.
>>>
>>>Definition: Query Solution 
>>>
>>>A Query Solution is a Pattern Solution for the Query Pattern. A
>>>substitution in a query solution only contains variables mentioned in
>>>the query.
>>>
>>
>>suggest:
>>
>>Given a Query Pattern, a Query Solution is one of its Pattern Solutions
>>whose substitutions only contains variables mentioned in the Query
>>Pattern.
> 
> 
> I don't see the need for a restriction to only contain variables mentioned in 
> the query.  Is there a technical reason for this?
> 
> Allowing other variables/values in a solution does no harm as far as I can see 
> and allows for later extension to nested queries.
> 
> I have to change the Query Results from saying plain "all" because of variable 
> inference capabilities.

I will add to the definition of basic pattern that every variable mentioned in 
the baisc pattern must be mentioned in the solution to the basic pattern.  This, 
I think, falls out naturally by "entails" so it will be in the text, not teh 
definition.

	Andy
Received on Thursday, 19 May 2005 11:37:01 UTC

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