Turtle Format

OWLGraph accepts ontologies in Turtle (Terse RDF Triple Language) format — a compact, human-readable syntax for RDF data.

Basic Structure

A Turtle file consists of prefix declarations and triple statements:

@prefix : <http://example.org/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

:Animal a owl:Class .
:Dog a owl:Class ; rdfs:subClassOf :Animal .

Prefixes

Prefixes are shorthand for long IRIs:

@prefix : <http://example.org/> .        # Default namespace
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

The first four are required for most ontologies. :Animal expands to <http://example.org/Animal>.

Triples

Every statement is a subject-predicate-object triple ending with .:

:Dog a owl:Class .
:Dog rdfs:subClassOf :Animal .

Shorthand: Semicolons and Commas

Semicolon (;) — same subject, different predicate:

:Dog a owl:Class ;
    rdfs:subClassOf :Animal ;
    rdfs:label "Dog" .

Comma (,) — same subject and predicate, different objects:

:Dog owl:disjointWith :Cat , :Bird .

Classes

# Named class
:Animal a owl:Class .

# Subclass
:Mammal a owl:Class ;
    rdfs:subClassOf :Animal .

# Disjoint classes
:Dog owl:disjointWith :Cat .

# Equivalent classes
:Canine owl:equivalentClass :Dog .

Object Properties

:hasOwner a owl:ObjectProperty ;
    rdfs:domain :Animal ;
    rdfs:range :Person .

:isOwnerOf a owl:ObjectProperty ;
    owl:inverseOf :hasOwner .

:friendOf a owl:ObjectProperty , owl:SymmetricProperty .

:locatedIn a owl:ObjectProperty , owl:TransitiveProperty .

:hasParent a owl:ObjectProperty .
:hasGrandparent a owl:ObjectProperty ;
    owl:propertyChainAxiom ( :hasParent :hasParent ) .

Data Properties

:name a owl:DatatypeProperty ;
    rdfs:range xsd:string ;
    a owl:FunctionalProperty .

:age a owl:DatatypeProperty ;
    rdfs:range xsd:integer .

:birthDate a owl:DatatypeProperty ;
    rdfs:range xsd:date .

Supported Datatypes

XSD Type	Dgraph Type	Example
`xsd:string`	`string`	`"hello"`
`xsd:integer`	`int`	`42`
`xsd:float`	`float`	`3.14`
`xsd:boolean`	`bool`	`true`
`xsd:date`	`datetime`	`"2024-01-15"`
`xsd:dateTime`	`datetime`	`"2024-01-15T10:30:00Z"`

Comments

# This is a comment
:Animal a owl:Class .  # Inline comment

Common Patterns

Ontology Declaration

<http://example.org/ontology> a owl:Ontology ;
    rdfs:label "My Ontology" ;
    owl:versionInfo "1.0" .

Complete Example

@prefix : <http://example.org/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

# Classes
:Animal a owl:Class .
:Mammal a owl:Class ; rdfs:subClassOf :Animal .
:Dog a owl:Class ; rdfs:subClassOf :Mammal .
:Cat a owl:Class ; rdfs:subClassOf :Mammal .
:Dog owl:disjointWith :Cat .

# Properties
:name a owl:DatatypeProperty ; rdfs:range xsd:string .
:hasOwner a owl:ObjectProperty ;
    rdfs:domain :Animal ; rdfs:range :Person .
:isOwnerOf a owl:ObjectProperty ;
    owl:inverseOf :hasOwner .

# Persons
:Person a owl:Class .