The meeting was attended, in whole or in part, by Michael Genesereth (host), Michael Gruninger (editor), Pat Hayes, John McCarthy, Chris Menzel, Adam Pease, John Sowa, Mark Stickel, and Charles White.
Two options were discussed:
The group decided to adopt the abstract syntax approach.
Each concrete syntax would share the same character encoding.
How do we specify the abstract syntax?
If EBNF is sufficient, we will use that
The following people will be liaisons to other standards projects:
Relationships between sorts and the Web ontology languages
Mark: Sort names are disjoint from predicate names; we do not want to infer new sort information
Mark: we need sort symbols in the language, but we don’t need a way of specifying the sorts themselves. In the KIF syntax, we have a provision for sort symbols, but the relationship between sorts is not addressed within the language itself. A sort system is a “plug-in” to KIF.
Pat: A sorted language is processed at parse time, without inference; with this criterion, the axiomatic approach does not define a sorted language at all.
What inferences can be made in a sorted language that would not be made in an unsorted language?
Sorted KIF will provide for:
What will be the new logical symbols for sorts?
Issues with Sort Declarations:
What is a classifier theory?
This may be closer to a “classifier engine” (API) that responds to queries about sorts; we would specify an interface that given a set of sort symbols returns their intersection. This will be a special form of ontology importation. e.g. (sort-theory URI). We could also consider sort theories to be analogous to foreign function calls.
What does this mean for a declarative language? I.e. what are the consequences of this importation with respect to model theory?
Sowa: Can restricted quantifiers faithfully play the role of a sorted language?
What is the syntax for restricted quantifiers?
Option 1: (forall ((?x :sort dog) (?y :sort cat)) (chases ?x ?y))
Option 2: (forall ((?x dog) (?y cat)) (chases ?x ?y))
Variant 1: (forall ((?x dog) (?y cat) (chases ?x ?y) (?z human)) (owner ?z ?x))
Variant 2: (forall ((dog ?x) (cat ?y)) (chases ?x ?y))
Note: Option 2 is satisfied by the BNF of KIF98
Example with Boolean combinations of sorts:
(forall (?x (& Sort1 Sort2)) (predicate ?x))
Should we allow sequence variables in arbitrary position if we don’t have a complete implementation?
Do modules have names, or do we assign names to individual axioms/sentences?
What exactly is a module?
Any solution to this issue should be reusable in MetaKIF when we name propositions at the metalevel.
Conformance to KIF is defined with respect to software applications.
A syntactic software application shall be conformant if it is able to parse a set of KIF sentences.
Conformance for inference systems is defined in the draft.
The purely syntactic notion of conformance that applies to applications such as parsers, translators, and editors
Alternative: Every conforming system must be able to at least parse an arbitrary KIF sentence.
Proposed conformance levels for sequence variables
Proposed syntactic conformance levels
Proposed conformance levels below first-order
Predefine a small set of classes, but allow the extension of this set within MetaCL
We need to be able to quantify into quote (at least to write axiom schemae), but you can’t quantify over an ill-formed expression.
What would this mean for sequence quantifiers in the metalanguage?
Do we want to include explicit datatypes in Common Logic?
i. In this approach, we are “importing” datatypes rather than explicitly defining them within KIF. The external specification of the datatypes plays the role of the classifier theory.
Do we want a string quote operator in the basic language (MetaKIF would contain the structural quote)?
Mike Genesereth advocated the inclusion of features to support closed world assumptions and related nonmonotonic reasoning; there was little broad discussion of this topic.
We are renaming the project to be Common Logic
Resume monthly telecon schedule (beginning April 23)
Chris will create a website for the project on his tamu server.
(add John to kif list as firstname.lastname@example.org)