Enabling Unambiguous GRDDL Results David Booth <dbooth@hp.com> Presentation to GRDDL Working Group, 20-June-2007 This document: http://dbooth.org/2007/grddl/ambiguity.ppt

What this issue is about Given an XML document, what RDF did the GRDDL transformation author intend to denote? Document receiver needs to be able to determine precisely what graph the XML document was intended to denote Critical when XML document is a serialization of RDF GRDDL transformation says how to deserialize 12 January 2019

What this issue is NOT about NOT about desired ambiguity Transformation author may intend variable results Can be useful sometimes -- a feature, not a bug NOT about eliminating ambiguity that the transformation author is willing to accept NOT about forcing the transformation author to be unambiguous NOT about requiring the GRDDL-aware agent to actually produce the transformation author's intended results Users may not need them all, for example This is only about giving the transformation author the ability to be unambiguous if desired 12 January 2019

Kinds of unwanted ambiguity 1. Wrong results. Results contain different triples than intended. Source of problem: ambiguous parsing/pre-processing Proposed solutions: Proposal 1b part 1, or Proposal 2b part 1 2. Subsetting. User unknowingly gets a proper subset of the intended results, while believing that he/she got all of them. Source of problem: Lack of a definition of "complete GRDDL results" Proposed solution: WG Note Proposal 1b parts 2, 3 & 4 12 January 2019

Proposal 1b part 1: Partial solution Proposal: Change input of GRDDL transformation from XPath node tree to representation Observations: Reduces unwanted ambiguity problem Permits transformation author to reduce variability in the "transformation application" step Simple normative change No changes to test cases 12 January 2019

Proposal 2b part 1: Better solution Change input of GRDDL transformation from XPath node tree to representation; and Specify that parsing is minimal, non-validating/me wn/ Observations: Reduces unwanted ambiguity problem Permits transformation author to reduce variability in the "transformation application" step Simple normative change No changes to test cases 12 January 2019

Leaving the door open to a WG Note on "Complete GRDDL Results" Note could define "complete GRDDL results" Based on existing sec. 7 algorithm Not required to be implemented Not on our critical path - could be done anytime before the WG closes 12 January 2019

Proposed changes to leave the door open on such a Note a. Add one sentence to Faithful Renditions. b. Add non-committal mention of possible WG Note. 12 January 2019

BACKUP SLIDES 12 January 2019

Variability in results -- current spec Transformation Determination Transformation Application GRDDL Transf. Select Representation Parse XPath node tree RDF XSLT/ other XML Doc 12 January 2019

Proposal 1b: Partial solution Transformation Determination Transformation Application GRDDL Transf. Select Representation Parse XPath node tree RDF XSLT/ other XML Doc Reduces problem in "transformation application" step But not in "transformation determination" step 12 January 2019

Proposal 2b: Full(?) solution Transformation Determination Transformation Application GRDDL Transf. Select Representation Parse XPath node tree RDF XSLT/ other XML Doc Limits parsing to minimum, non-validating 12 January 2019