| Abstract | This paper describes a technique for infor-mation mediation when multiple heterogeneous knowl-
edge and data servers are to be accessed during query
processing. One problem is building an intelligent in-
terface between each knowledge server (KS) and its
processor (KP); and the second is to provide interoper-
ability among multiple KP/KS so that a query may be
answered using information from multiple sources. We
present example scenarios which highlight these prob-
lems and then outline query mapping and transforma-
tion techniques that are applicable. The techniques
for solving the interoperability problems involve rep-
resentations in some canonical form. This includes a
canonical representation (CR) corresponding to each
KP/KS pair and a merged CR (MCR) to represent the
mapping among the CRs. The MCR and CRs include
relevant information obtained from a source query, and
heterogeneous mapping (het-map) information, for all
possible mappings among the multiple servers. The
knowledge in the canonical form must be represented
so that it can be easily accessed during query transfor-
mation. We use an example of translating queries from
an object schema to a relational schema to illustrate
typical knowledge that must be represented in some
canonical form. We use a high level logical language,
F-logic, to represent the heterogeneous mapping (het-
map) and query transformation information as a set
of declarative rules, in the canonical form.
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