Re: PROV-ISSUE-536: Notation Section 2.3 [prov-n]

Dear all,

Find below a proposed response to ISSUE-536. Feedback appreciated, as 
always!

Luc


>       ISSUE-536 (Syntax Ambiguity and - marker)
>
>   * Original
>     email:http://lists.w3.org/Archives/Public/public-prov-wg/2012Sep/0130.html
>   * Tracker:http://www.w3.org/2011/prov/track/issues/536
>   * Group Response:
>       o The comment refers to the previous working draft. In
>         particular, the syntax ambiguity issue is superseded by the
>         syntax published in the Last Call Working Draft.
>       o Our response to ISSUE-537 explains how optional identifiers
>         should be expressed in PROV-N.
>       o The proper syntax for the suggested examples would be as follows:
>           + wasDerivedFrom(d; e2, e1) // semi-colon separates
>             derivation identifier from other arguments
>           + wasDerivedFrom(e2, e1, a, -, -) // where absent usage and
>             generation are marked with -
>       o The author also queries the choice of the special marker '-'.
>         We had to use a symbol that was not a qualified name: - is not
>         allowed as a local name.
>       o The author suggests using NULL, but this is a valid local name
>         (and hence, a valid qualified name).
>       o Our response to ISSUE-533 addresses the named attributes option.
>   * References:
>   * Changes to the document: none
>   * Original author's acknowledgement:
>
>
>     [edit
>     <http://www.w3.org/2011/prov/wiki/index.php?title=ResponsesToPublicComments&action=edit&section=50>]
>


On 10/09/12 10:54, Provenance Working Group Issue Tracker wrote:
> PROV-ISSUE-536: Notation Section 2.3 [prov-n]
>
> http://www.w3.org/2011/prov/track/issues/536
>
> Raised by: Paolo Missier
> On product: prov-n
>
> Is the use of "-" to indicate a missing term a standard convention? It seems unintuitive and potentially error-prone. NULL might be better if positional attributes are used (this issue is moot if named attributes are used; see issue 533 regarding "notation of attributes":
> https://www.w3.org/2011/prov/track/issues/533
>
>
> There seems to be ambiguity in the syntax when the first parameter is option. For example, if both "wasDerivedFrom(e2, e1, a)" and "wasDerivedFrom(d, e2, e1)" are valid expressions, how can they be differentiated?
>
> Example 1: (e2, e1, a) is an acceptable form of (e2, e1, a, -, -) Example 2: (d, e2, e1) is an acceptable form of (d, e2, e1, -, -, -)
>
> Without named attributes, it is not possible to unambiguously determine how to parse "wasDerivedFrom(1, 2, 3)". Is it in the form of Example 1 or Example 2?
>
>
>
>

-- 
Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm