A posting from John Sowa summarizes the results of a recent Common Logic Standardization Meeting held at Stanford University which proposes an ISO Common Logic (CL) Standard related to Knowledge Interchange Format (KIF) and Conceptual Graphs (CGs). CL is to be "defined by an abstract syntax, which specifies the major categories, such as Quantifier, Negation, and Conjunction, without specifying any concrete symbols for writing them. The CL standard will also contain grammars for three concrete syntaxes: KIF, CGIF (the CG interchange format), and traditional predicate calculus (TPC) with a Unicode encoding of the commonly used symbols. Besides the three concrete syntaxes that are currently planned for the standard, [the group] discussed plans for an XML-based syntax [XML-CL] that could be mapped directly to the abstract syntax. For example, the abstract category Conjunction would be expressed differently in each of the three concrete syntaxes. Instead of giving a separate mapping to XML from each of the concrete syntaxes, it would be simpler to map the abstract category directly to the XML form <conjunction>... </conjunction> without specifying which of the three concrete syntaxes was the original source or the intended target of the information." The development team "hopes that the CL standard can be used for many other languages that have a declarative semantics, such as RDF, UML, DAML, or Topic Maps. There will be an XML representation of the abstract categories, which will conform to all accepted W3C standards. There may also be XML representations of the concrete syntaxes as well; TPC notation will require Unicode for the special logical symbols, but they could also be represented, as in HTML and XML, by symbols like &forall; or &exist;."

Background, from the NWI provisional proposal of 2001-10-01: "The standard will be a language designed for use in the interchange of knowledge among disparate computer systems. It will be a logically comprehensive language with a declarative semantics, and it will provide for the representation of knowledge about knowledge. Two semantically equivalent syntaxes will be specified within the standard -- the Knowledge Interchange Format (KIF) and Conceptual Graphs (CG). The standard will be divided into three parts. Part 1 (First-Order Logic) specifies the syntax and semantics of a language equivalent to first-order logic. Part 2 (Infinitary Logic) is an expansion of the language of Part 1 that specifies the syntax and semantics of an infinitary logic. Part 3 (MetaKIF) is an expansion of the language of Part 1 that formalizes the syntax and semantics of the metatheory of first-order logic... The creation of disparate knowledge-based systems by different programmers, at different times, and in different knowledge representation languages has led to barriers to interoperability among these systems. By providing a logically comprehensive language, KIF will have the capability of expressing arbitrary logical sentences within these systems. A declarative semantics will make it possible to understand the meaning of expressions in the language without appeal to an interpreter for manipulating those expressions. Although there are many areas of continuing research on knowledge representation, only those concepts that are universally accepted within the knowledge representation and mathematical logic communities will be proposed for standardization. This will be restricted to languages that are equivalent in expressiveness to first-order logic, infinitary logic, and the metatheory of first-order logic..."