@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix : <http://www.w3.org/2000/01/rdf-schema#> .
@prefix dct: <http://purl.org/dc/terms/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix dgb: <https://discoursegraphs.com/schema/dg_base#> .
@prefix bibo: <http://purl.org/ontology/bibo/> .
@prefix status: <http://purl.org/ontology/bibo/status/> .

<https://discoursegraphs.com/schema/dg_base#> a owl:Ontology;
    dct:created "2025-12-22" ;
    rdfs:comment "DiscourseGraph foundation vocabulary"@en ;
    rdfs:label "DiscourseGraph foundation vocabulary"@en ;
    bibo:status status:draft;
    owl:versionInfo "0 (tentative)".

# This is inspired by https://hyperknowledge.org/schemas/hyperknowledge_frames.ttl
# and topic mapping

dgb:Node a owl:Class;
    rdfs:comment "Superclass of all DiscourseGraph nodes"@en .

# NodeSchema is the metaclass of node types; it is equivalent to being a subclass of dgb:Node,
# so either `X a dgb:NodeSchema` or `X rdfs:subClassOf dgb:Node` can be asserted and the other inferred.
# (OWL Full: OWL 2 DL forbids restrictions on rdfs:subClassOf. OWL RL reasoners apply it.)
# Side effect: reasoners that derive reflexive subClassOf will also infer dgb:Node a dgb:NodeSchema
# (and likewise dgb:RelationInstance a dgb:AbstractRelationDef, below).
dgb:NodeSchema
    rdfs:subClassOf owl:Class;
    owl:equivalentClass [a owl:Restriction; owl:onProperty rdfs:subClassOf; owl:hasValue dgb:Node];
    rdfs:comment "Subclasses of DiscourseGraph nodes"@en .

# The declared domain and range of a role. Restrictions on rdfs:domain/rdfs:range would also
# apply to inferred superclass domains (up to owl:Thing), so roles declare theirs with these
# subproperties; rdfs:domain and rdfs:range are still inferred (and may also be asserted).
dgb:roleDomain rdfs:subPropertyOf rdfs:domain;
    rdfs:comment "The declared domain of a role: the node schema that has the role"@en .

dgb:roleRange rdfs:subPropertyOf rdfs:range;
    rdfs:comment "The declared range of a role: the node schema of the role's values"@en .

dgb:Role
    rdfs:subClassOf owl:ObjectProperty,
        [a owl:Restriction; owl:onProperty dgb:roleDomain ; owl:allValuesFrom dgb:NodeSchema ],
        [a owl:Restriction; owl:onProperty dgb:roleRange ; owl:allValuesFrom dgb:NodeSchema ];
    rdfs:comment "A role within a node schema"@en .


# Likewise, relation definitions are (punned) classes of relation instances.
dgb:AbstractRelationDef rdfs:subClassOf dgb:NodeSchema;
  owl:equivalentClass [a owl:Restriction; owl:onProperty rdfs:subClassOf; owl:hasValue dgb:RelationInstance];
  rdfs:comment "DiscourseGraph relation definitions"@en.

dgb:RelationDef rdfs:subClassOf owl:ObjectProperty, dgb:AbstractRelationDef;
  rdfs:comment "DiscourseGraph relations"@en.


dgb:RelationInstance rdfs:subClassOf rdf:Statement, dgb:Node,
  [a owl:Restriction; owl:onProperty rdf:predicate ; owl:allValuesFrom dgb:RelationDef ].

dgb:source a dgb:Role ;
    rdfs:subPropertyOf rdf:subject ;
    dgb:roleDomain dgb:RelationInstance ;
    dgb:roleRange dgb:Node ;
    rdfs:domain dgb:RelationInstance ;
    rdfs:range dgb:Node ;
    rdfs:comment "The source of a binary relation"@en .

dgb:destination a dgb:Role ;
    rdfs:subPropertyOf rdf:object ;
    dgb:roleDomain dgb:RelationInstance ;
    dgb:roleRange dgb:Node ;
    rdfs:domain dgb:RelationInstance ;
    rdfs:range dgb:Node ;
    rdfs:comment "The destination of a binary relation"@en .

dgb:textRefersToNode a owl:ObjectProperty;
  rdfs:domain dgb:Node;
  rdfs:range dgb:Node;
  rdfs:comment "The text of a node refers to another node"@en .


# examples

# :x a dgb:NodeSchema .
# :y a dgb:NodeSchema .
# :x0 a :x.
# :y0 a :y.
# :r a dgb:NodeSchema.
# :x_r a dgb:Role ;
#     dgb:roleDomain :r ;
#     dgb:roleRange :x .

# :r0 a :r;
#  :x_r :x0.

# :br a dgb:RelationDef;
#   rdfs:domain :x;
#   rdfs:range :y;

# :br0
#  a dgb:RelationInstance;
#  rdf:predicate :br ;
#  dgb:source :x0 ;
#  dgb:destination :y0 ;

# # This is "about" :x0 :br :y0;

# Note: we could also use punning, and define
# :br rdfs:subClassOf dgb:RelationInstance,
#   [a owl:Restriction;
#   owl:onProperty rdf:predicate ;
#   owl:hasValue :br ].
# Then we can more simply state
# :br0
#  a :br;
#  dgb:source :x0 ;
#  dgb:destination :y0 ;