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1package rsacomb
2
3/* Java imports */
4import org.semanticweb.owlapi.model.{
5 OWLAxiom,
6 OWLSubClassOfAxiom,
7 OWLEquivalentClassesAxiom
8}
9import org.semanticweb.owlapi.model.{
10 OWLObjectPropertyExpression,
11 OWLSubObjectPropertyOfAxiom,
12 OWLClass,
13 OWLClassExpression,
14 OWLObjectSomeValuesFrom,
15 OWLObjectMaxCardinality
16}
17import org.semanticweb.owlapi.model.ClassExpressionType
18import org.semanticweb.owlapi.model.{
19 OWLAxiomVisitorEx,
20 OWLClassExpressionVisitorEx
21}
22import org.semanticweb.owlapi.model.OWLObjectProperty
23import scala.collection.JavaConverters._
24
25/* Wrapper trait for the implicit class `RSAAxiom`.
26 */
27trait RSAAxiom {
28
29 /* Identifies some of the axiom types in a Horn-ALCHOIQ ontology
30 * in normal form. Refer to the paper for more details on the
31 * chosen names.
32 */
33 private sealed trait RSAAxiomType
34 private object RSAAxiomType {
35 case object T3 extends RSAAxiomType // ∃R.A ⊑ B
36 case object T3top extends RSAAxiomType // ∃R.⊤ ⊑ B
37 case object T4 extends RSAAxiomType // A ⊑ ≤1R.B
38 case object T5 extends RSAAxiomType // A ⊑ ∃R.B
39 }
40
41 object RSAAxiom {
42
43 def hashed(
44 cls1: OWLClass,
45 prop: OWLObjectPropertyExpression,
46 cls2: OWLClass
47 ): String =
48 (cls1, prop, cls2).hashCode.toString
49
50 }
51
52 /* Implements additional features on top of `OWLAxiom` from
53 * the OWLAPI.
54 */
55 implicit class RSAAxiom(axiom: OWLAxiom) {
56
57 /* Detecting axiom types:
58 *
59 * In order to reason about role unsafety in Horn-ALCHOIQ
60 * ontologies we need to detect and filter axioms by their
61 * "type".
62 *
63 * This is a simple implementation following the Visitor
64 * pattern imposed by the OWLAPI.
65 */
66 private class RSAAxiomTypeDetector(t: RSAAxiomType)
67 extends OWLAxiomVisitorEx[Boolean] {
68 override def visit(axiom: OWLSubClassOfAxiom): Boolean = {
69 val sub = axiom.getSubClass().getClassExpressionType()
70 val sup = axiom.getSuperClass().getClassExpressionType()
71 t match {
72 case RSAAxiomType.T3top => // ∃R.⊤ ⊑ B
73 axiom.isT3 && axiom
74 .getSubClass()
75 .asInstanceOf[OWLObjectSomeValuesFrom]
76 .getFiller
77 .isOWLThing
78 case RSAAxiomType.T3 => // ∃R.A ⊑ B
79 sub == ClassExpressionType.OBJECT_SOME_VALUES_FROM && sup == ClassExpressionType.OWL_CLASS
80 case RSAAxiomType.T4 => // A ⊑ ≤1R.B
81 sub == ClassExpressionType.OWL_CLASS && sup == ClassExpressionType.OBJECT_MAX_CARDINALITY
82 case RSAAxiomType.T5 => // A ⊑ ∃R.B
83 sub == ClassExpressionType.OWL_CLASS && sup == ClassExpressionType.OBJECT_SOME_VALUES_FROM
84 }
85 }
86
87 override def visit(axiom: OWLEquivalentClassesAxiom): Boolean = {
88 // TODO
89 false
90 }
91
92 def doDefault(axiom: OWLAxiom): Boolean = false
93 }
94
95 private def isOfType(t: RSAAxiomType): Boolean = {
96 val visitor = new RSAAxiomTypeDetector(t)
97 axiom.accept(visitor)
98 }
99
100 /* Exposed methods */
101 def isT3top: Boolean = isOfType(RSAAxiomType.T3top)
102 def isT3: Boolean = isOfType(RSAAxiomType.T3)
103 def isT4: Boolean = isOfType(RSAAxiomType.T4)
104 def isT5: Boolean = isOfType(RSAAxiomType.T5)
105
106 /* Extracting ObjectPropertyExpressions from axioms
107 *
108 * This extracts all ObjectPropertyExpressions from a given
109 * axiom. While the implementation is generic we use it on axioms
110 * of specific types (see above).
111 *
112 * NOTE: it is not possible to use the `objectPropertyInSignature`
113 * method of `OWLAxiom` because it returns all "role names" involved
114 * in the signature of an axiom. In particular we won't get the inverse
115 * of a role if this appears in the axiom (but we will get the role
116 * itself instead).
117 */
118 lazy val objectPropertyExpressionsInSignature
119 : List[OWLObjectPropertyExpression] =
120 axiom match {
121 case a: OWLSubClassOfAxiom =>
122 rolesInExpr(a.getSubClass) ++ rolesInExpr(a.getSuperClass)
123 case a: OWLEquivalentClassesAxiom =>
124 a.getClassExpressions.asScala.toList.flatMap(rolesInExpr(_))
125 case a: OWLSubObjectPropertyOfAxiom =>
126 List(a.getSubProperty, a.getSuperProperty)
127 case _ => List()
128 }
129
130 private def rolesInExpr(
131 expr: OWLClassExpression
132 ): List[OWLObjectPropertyExpression] =
133 expr match {
134 case e: OWLObjectSomeValuesFrom => List(e.getProperty)
135 case e: OWLObjectMaxCardinality => List(e.getProperty)
136 case _ => List()
137 }
138
139 lazy val toTriple: Option[(OWLClass, OWLObjectProperty, OWLClass)] =
140 for {
141 subClass <- Some(axiom) collect { case a: OWLSubClassOfAxiom => a }
142 cls1 <- Some(subClass.getSubClass) collect { case a: OWLClass => a }
143 someValues <- Some(subClass.getSuperClass) collect {
144 case a: OWLObjectSomeValuesFrom => a
145 }
146 prop <- Some(someValues.getProperty) collect {
147 case a: OWLObjectProperty => a
148 }
149 cls2 <- Some(someValues.getFiller) collect { case a: OWLClass => a }
150 } yield (cls1, prop, cls2)
151
152 lazy val hashed: String = (RSAAxiom.hashed _) tupled toTriple.get
153 }
154
155} // trait RSAAxiom
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