Matters

Data Semantics Revisited: Databases and the Semantic Web
"Mapping Graphs
* The graph associated with each mapping continuum is
acyclic and has one or more anchors, its semantic
models (“ontologies” in Semantic Web jargon).
* The semantic models constitute formally represented
encyclopedias on a given subject matter; they are
application-independent, specified in an expressive
modeling language (e.g., OWL.)
* Every model has an associated (semantic) mapping to
one or more other models."

"Models
* A model is intended to answer a specific set of
questions about its subject matter (a model has a
purpose!) [Ladkin97].
* For example, a model airplane can answer questions
about the dimensions and aerodynamics of an aircraft;
but not questions about its engine power, physical
makeup, etc.
* For every model, we need a translation function
(mapping) that will translate a query about the subject
matter into one about the model (where applicable), and
vice versa for the result of the query."

"Types of Models
* I-models (intentional): Consist of a set of predicates
with associated axioms; Database schemas (with
integrity constraints), but also logical theories fit here.
* E-models (extensional): These have set-theoretic
constructions, and query answering based on settheoretic
relationships; Tarskian and Kripke models, but
also databases, fit here.
* C-models (computational): These are characterized by
the fact that query answering is produced by running
programs, e.g., a simulation program."

I think HTM (Hierarchical Temporal Memory) models should be added to the above list.