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/*
* Copyright 2020, 2021 KRR Oxford
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package uk.ac.ox.cs.rsacomb.converter
import org.semanticweb.owlapi.model.OWLAxiom
import tech.oxfordsemantic.jrdfox.logic.Datatype
import tech.oxfordsemantic.jrdfox.logic.expression.{Literal, IRI}
import uk.ac.ox.cs.rsacomb.util.RSA
sealed trait SkolemStrategy {
def dup(a: OWLAxiom): SkolemStrategy
}
/** No skolemization.
*
* @example role `R` from
* {{{
* ∃R.A ⊑ B
* }}}
* to
* {{{
* R(x,y), B(y) -> B(x)
* }}}
*/
case object NoSkolem extends SkolemStrategy {
def dup(a: OWLAxiom): SkolemStrategy = this
}
/** Functional skolemization
*
* The factory object should be used to create new instances of the
* class.
*
* @example role `R` from
* {{{
* A ⊑ ∃R.B
* }}}
* to
* {{{
* A(x) -> R(x,f(x)), B(f(x))
* }}}
* for `f`, fresh function uniquely associated with the input axiom.
*
* RDFox does not support function symbols. We can still implement
* function symbols combining the `BIND` operator with the `SKOLEM`
* operator as such:
* {{{
* A(x), BIND(y, SKOLEM("f", x)) -> R(x,y), B(y)
* }}}
* The first argument of a `SKOLEM` call '''must''' be a literal string
* (ideally identifing the simulated function name).
*
* @note this requirement is not enforced by RDFox, that will fail
* silently if a string argument is omitted.
*/
case class Standard(axiom: OWLAxiom)(implicit toString: (OWLAxiom) => String)
extends SkolemStrategy {
def dup(_axiom: OWLAxiom): Standard = copy(axiom = _axiom)(toString)
lazy val name = s"f_${toString(axiom)}"
}
/** Constant skolemization
*
* The factory object should be used to create new instances of the
* class.
*
* @example role `R` from
* {{{
* A ⊑ ∃R.B
* }}}
* to
* {{{
* A(y) -> R(x,c), B(c)
* }}}
* for `c`, fresh constant '''uniquely''' associated with the input
* axiom
*/
case class Constant(axiom: OWLAxiom)(implicit toString: (OWLAxiom) => String)
extends SkolemStrategy {
def dup(_axiom: OWLAxiom): Constant = copy(axiom = _axiom)(toString)
lazy val iri = RSA(s"c_${toString(axiom)}")
}
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