A Note on CIF & RIF

CIF and RIF are both interchange formats for logic expressions on the Web. CIF is designed to express fully quantified constraints based on the CoLan language designed by Peter Gray and Nick Bassiliades. The current Semantic Web version of CIF extends SWRL, essentially by providing a syntax for quantifiers and nested implications.

It is expected that CIF will evolve to use RIF in place of SWRL as the new format takes shape. If - as is currently planned - Phase 1 RIF is essentially Horn Logic, we will look at using the RIF implication syntax instead of SWRL. Looking further ahead, if Phase 2 RIF includes full FOL then this format may wholly subsume CIF. At that point it is conceivable that we would simply define CIF as a subset of RIF: constraints would be interchanged in RIF itself.

To this end, we support the RIF effort, especially the move to capturing full FOL in Phase 2 RIF.

NOTE: RIF and Soft CSPs

As a qualifier to the above, we note that there does not appear to be any current plan to incorporate mechanisms to define soft CSPs in RIF. The motivation for soft CSP representations in the Semantic Web context is set out in:

pdf Handling Soft Constraints in the Semantic Web Architecture
Alun Preece, Stuart Chalmers, Craig McKenzie, Jeff Pan, & Peter Gray (2006)
To be presented at RoW2006 Reasoning on the Web at WWW2006, Edinburgh, UK

We foresee two possibilities:

  1. a suitable method for expressing soft constraints becomes incorporated into RIF, potentially as part of the Phase 2 efforts;
  2. our existing soft CSP ontology (or a future version of it) may continue to be used, with RIF expressions allowed as the values of the hasExpression property.


Last updated: 21 March 2006   A Preece