F2F1 Minutes Session 1
This is part of F2F1 Minutes
OWL Working Group Meeting Minutes, 06 December 2007
DRAFT. Currently Under Review
See also: IRC log
- Peter Patel-Schneider
Welcome, Logistics, Introductions
Bernardo Cuenca Grau
Carsten Lutz, Dresden (guest, joining)
Thomas Schneider (guest)
Sebastian Brandt (guest)
Matthew Horridge (guest)
Sean Bechhofer (guest from Manchester)
Robert Stevens (guest from Manchester)
Ian Horrocks (University of Manchester [sic])
OWL 1.0 Implementation Experience
Speaker - Matthew Horridge - slides
Matthew Horridge: implementing OWL DL experience
Matthew Horridge: problems - RDF and imports
Matthew Horridge: internal API is known as the OWL API - based on OWL abstract syntax
Matthew Horridge: use of OWL API means that different concrete syntaxes can be used
Matthew Horridge: problems with abstract syntax - distinguishing between, e.g., data and object properties
Matthew Horridge: effort required - RDF parser is vast majority of effort, everything else is much easier
Matthew Horridge: similar situation for OWL 1.1 API
Ivan Herman: what is the "RDF parser"
Matthew Horridge: RDF parser is just triples to internal API, not dealing with RDF/XML
Matthew Horridge: RDF mapping - want to be fast, small, and streaming
Matthew Horridge: streaming was too hard, so the parser was not streaming
Matthew Horridge: in new parser - parser is streaming, but still takes resources
Matthew Horridge: OWL XML is very verbose - causes problems
Jeremy Carroll: what is the size increase
Matthew Horridge: not sure - 3 to 5 times
Matthew Horridge: triples to OWL API was problematic - inversing a non-deterministic mapping
Matthew Horridge: OWL 1.1 thus has two mappings
Matthew Horridge: e.g., subclass (see slides)
Matthew Horridge: other problem - n-ary constructs go to n or n*n triples
Matthew Horridge: failures of round tripping cause problems
Matthew Horridge: missing type triples make ontologies officially non-parsable
Matthew Horridge: in many cases there is a fix, but sometimes the fix is not local (may require looking at imported ontologies)
Jeremy Carroll: declaration is good style - RDF graphs are unordered - so declarations can be non-local
Michael Smith: searching for declarations require two passes - which can be expensive
Alan Ruttenberg: why not do typing "as seen"
Boris Motik: this requires deferring processing, and is hard
Bijan Parsia: in any case, there is a lot of extra work to make the RDF parsing go through
Jeremy Carroll: there are implementations that do good jobs
Bijan Parsia: no - there are bugs
Jeremy Carroll: but you do get benefits - use of RDF
Bijan Parsia: but there is a cost
Jeremy Carroll: multiple vocab is an attempt to fix this?
Bijan Parsia: yes
Alan Ruttenberg: compatibility means that there is no way out
Ian Horrocks: if we make a better way, then the old versions will die out (eventually)
Matthew Horridge: imports issues
Matthew Horridge: if //...foo.... imports //...bar... what does it mean?
Matthew Horridge: name of an ontology or a location of an ontology
Matthew Horridge: what if the name and the location don't match
Matthew Horridge: imports on OWL DL is controlled by OWL S&AS 3.4
Matthew Horridge: OWL reference says imports is by location
Matthew Horridge: OWL guide says something confusing
Matthew Horridge: want some direct and normative statement
Matthew Horridge: solution was by name (essentially)
Matthew Horridge: what is the name of an ontology?
Matthew Horridge: guide is confusing
Matthew Horridge: test cases for OWL 1.0 were very useful - we need them for 1.1
Matthew Horridge: OWL 1.1 SS diagrams were useful
Jeremy Carroll: we need some time to talk about testing
Bijan Parsia: yes - infrastructure is needed
Jeremy Carroll: probably only need a short amount of time
Alan Rector (guest from Manchester)
Ratnesh Sahay (DERI Galway)
History (including OWLED)
Speaker - Bijan Parsia (no slides)
Bijan Parsia: OWLED - started in 2005 to let people interested in OWL design and use together
Bijan Parsia: there was about 1.5 years of experiece in OWL - there were complaints (particularly QCRs and datatypes)
Bijan Parsia: idea for a "bug fix" update to OWL - things that are relatively easy and wanted
Bijan Parsia: particularly wanted by users
Bijan Parsia: workshop was (largely) to discover what this new version would be
Bijan Parsia: workshop was adjacent to ISWC 2005 - about 60 participants
Bijan Parsia: desiderata for changes:
Bijan Parsia: 1/ requested by major users
Bijan Parsia: 2/ have effective reasoning methods
Bijan Parsia: 3/ will be implemented
Bijan Parsia: (alternatively commitment from users, well understood, committment from implementers)
Bijan Parsia: other goals: quiet whining, promote apps, improve spec, move forward, path for extensions, reduce species confusion (particularly DL/Lite)
Bijan Parsia: example - move OWL-S to OWL DL
Bijan Parsia: tool feature - coercion to OWL DL in Pellet
Jeremy Carroll: tools *should* do this
Bijan Parsia: *mostly* get the right thing
Bijan Parsia: there are still things that people want to do - e.g., lists
Bijan Parsia: I implemented shadow lists -- RDF Lists with a parallel vocabulary, just a different namespace. Pellet can do this silently.
Jeremy Carroll: can rdf:list be fixed?
Bijan Parsia: issues of modelling lists (eg, breaking them) affecting syntax
Alan Ruttenberg: are lists necessary?
Bijan Parsia: yes
Peter Patel-Schneider: Lists are only in RDF because OWL-WG demanded them.
Peter Patel-Schneider: We needed them for the OWL syntax
Deborah McGuinness: consensus on what do to?
Bijan Parsia: no, just consensus on desiderata
Bijan Parsia: OWL 1.1 design is driven by the three main desiderata
Carsten Lutz: are all three needed?
Bijan Parsia: not in all cases, but in most cases
Stability vs Missing Features
Jeremy Carroll: some groups want stability
Bijan Parsia: main desiderata do lean towards stability
Ivan Herman: there is still a long process to use OWL, so change is bad
Jeremy Carroll: HP didn't participate in OWLED due to financial desires
Alan Rector: missing features in OWL have hindered uptake
Bijan Parsia: currently missing feature is keys
Ivan Herman: different markets - some want more features, some want no change
Peter Patel-Schneider: why?
Bijan Parsia: why should people who are only taking taking part of OWL care about OWL being extended?
Sandro Hawke: This is "OWL Pixie Dust". People want some of the OWL Magic, without really knowing what OWL is or does for them......
Alan Rector: standards all change so why is new OWL a problem?
Alan Rector: there are issues with backward compatibility
Alan Rector: Standards grow, with backward compatibility. And sometimes there are mistakes that need to be fixed.
Ian Horrocks: maintenance is needed
Deborah McGuinness: users want transition path and backwards compatibility
Ivan Herman: we need to take care of stability concerns
Bijan Parsia: model of development - do lots of work outside W3C, then quick recommendation, repeat roughly yearly
Ivan Herman: stability - vague uneasiness (mostly)
Alan Ruttenberg: what can we do to help?
Ivan Herman: nothing, really
Sandro Hawke: if the perception is that OWL 1.0 is broken then that is even worse than the perception that things are unstable because we're working on 1.1
Alan Rector: for me OWL 1.0 is not usable - so I need OWL 1.1
Bijan Parsia: look for people who have real blockage and try to help them
Effect of OWLED
Bijan Parsia: Bijan: OWLED attendance and submissions have been growing
Bijan Parsia: many participants felt that OWLED gave them a voice
Bijan Parsia: OWLED experience has been positive
Bijan Parsia: testimonial from Kent Spackman (SNOMED person)