Sparrow Language

Intended audience

This document is intended for SEEK and Kepler developers. It is a DRAFT DESIGN DOCUMENT and does not reflect functionality as it currently exists in Kepler or SEEK. Comments and feedback are appreciated.

Introduction

Sparrow is a description-logic syntax that is meant as a "lightweight" alternative to RDF/S and OWL for defining ontologies. This document details the sparrow syntax. Note that in terms of expressivity, sparrow lies between RDF/S and OWL-DL.

Sparrow

Sparrow, like description logics, represent ontologies using concepts, roles, and individuals. We desribe each of these below.

Concepts

In sparrow, concepts are defined using sentences. For instance, we can introduce a new concept called 'Vegetarian' using the following sentence.

concept Vegetarian

This sentence simply states that the 'Vegetarian' is a concept. Note that the term 'concept' is a reserved word in the sparrow language. A concept can be further elaborated using concept axioms, which are essentially more complex sentences of a restricted form. Consider the following example.

concept Animal kind-of Organism

This sentence states that 'Animal' is a subconcept of 'Organism'. In other words, every animal is an organism. The term 'kind-of' is a reserved word (sometimes referred to as "is-a"). The sentence is considered an axiom because it is asserting a rule, or relationship, that is assumed to hold between 'Animal' and 'Organism'. Namely, that being an animal implies being an organism.

Both 'Animal' and 'Organism' are asserted as being concepts by this sentence. The sentence is equivalent to the following three sparrow sentences.

concept Organism
concept Animal
concept Animal kind-of Organism

Multiple sentences defining the same concept can be combined through conjunction (and). For example, the sentences:

concept Animal kind-of Organism
concept Animal kind-of not Plant

can be combined into the sentence:

concept Animal kind-of Organism and not Plant

Here the terms 'and' and 'not' are sparrow reserved words. The sentence states that an animal is an organism but not a plant. For convenience, 'and' can be replaced by the term 'but', for example:

concept Animal kind-of Organism but not Plant

Capitalization is not important in sparrow, thus the previous sentence is equivalent to:

CONCEPT animal KIND-OF organism BUT NOT plant

Another type of concept axiom that can be expressed in sparrow is equivalence among concepts. For example, consider the following sentence.

concept Human same-as Person

This sentence asserts that 'Human' and 'Person' denote the same concept.

Roles

A more complex example ...

concept Macromolecule same-as Molecule that contains at-least 100 Atom

Individuals

Packaging Sparrow Ontologies

A sparrow ontology is made up of a set of sparrow sentences. Typically an ontology would be stored in a single file, however, a file could conceivable store multiple ontologies. An ontology is started with the 'ontology' reserved word. An ontology can import definitions from other ontologies. The following example starts an ontology definition and imports an external ontology.

ontology myOnt 'http://seek.ecoinformatics.org/ontology1#'
import yourOnt 'http://seek.ecoinformatics.org/ontology2#'

...

Sparrow Reserved Wordsf