# Re: Restructure definition of Basic Graph Pattern and pattern match (sec 2.4)

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Mon, 13 Jun 2005 14:47:43 +0100
CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>
```

Jeen Broekstra wrote:
> SPARQL language editor's draft rev 1.379
> http://www.w3.org/2001/sw/DataAccess/rq23/
>
> In section 2.4 the terms 'Pattern Solution', 'Query Solution' and
> 'Basic Graph Pattern' are defined,
>
> The definition of Basic Graph Pattern includes what it means to match
> against a graph. It would be better to create a separate definition
> for this, called 'Graph Pattern Match'. The definition of 'Basic Graph
> Pattern' can then be moved to the start of the section, and in any
> case I think an explicit definition of pattern match, that links graph
> patterns to solutions, is a lot clearer.
>
> Also, the current definition of a match is imprecise. It uses the
> notion 'entails' without specifying what that means. Is that simple
> entailment, RDF(S) entailment, or an entirely different, more loose
> form of entailment? I request instead using the notion of 'subgraph'
> for defining a match.

It has already gone back to being "subgraph" to avoid entailment.  Simple
entailment does not add anything (except a lot of blank nodes).  "Entailment"
does not define what kind.

The match can be a subgraph of an entailed graph, putting the entailment outside
the SPARQL doc.

>
> Suggested definitions:
>
>    Definition: *Basic Graph Pattern*
>
>    A /basic graph pattern/ is a set of Triple Patterns.
>
>    Definition: *Graph Pattern Match*
>
>    A graph pattern /matches/ on a graph G with pattern solution S iff
>    S(GP) is a non-empty subgraph of G.

This is at odds with later definitions.  This defn is only basic patterns.

I have left order as is but 2.4 is split:

2.4 Pattern Solutions
2.5 Basic Graph Patterns

and old 2.5 (example) is part of new 2.5 as well.

>
> Jeen

v1.391
Andy
```
Received on Monday, 13 June 2005 13:51:27 UTC

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