diff --git a/src/core/parser_old/expression_factory.cpp b/src/core/parser_old/expression_factory.cpp
deleted file mode 100644
index 312e76ed..00000000
--- a/src/core/parser_old/expression_factory.cpp
+++ /dev/null
@@ -1,115 +0,0 @@
-#include "expression_factory.h"
-
-#include "expressions/booleans/empty.h"
-#include "expressions/booleans/inclusion.h"
-#include "expressions/booleans/nullary.h"
-#include "expressions/concepts/all.h"
-#include "expressions/concepts/and.h"
-#include "expressions/concepts/bot.h"
-#include "expressions/concepts/diff.h"
-#include "expressions/concepts/equal.h"
-#include "expressions/concepts/not.h"
-#include "expressions/concepts/one_of.h"
-#include "expressions/concepts/or.h"
-#include "expressions/concepts/projection.h"
-#include "expressions/concepts/primitive.h"
-#include "expressions/concepts/some.h"
-#include "expressions/concepts/subset.h"
-#include "expressions/concepts/top.h"
-#include "expressions/numericals/concept_distance.h"
-#include "expressions/numericals/count.h"
-#include "expressions/numericals/role_distance.h"
-#include "expressions/numericals/sum_concept_distance.h"
-#include "expressions/numericals/sum_role_distance.h"
-#include "expressions/roles/and.h"
-#include "expressions/roles/compose.h"
-#include "expressions/roles/diff.h"
-#include "expressions/roles/identity.h"
-#include "expressions/roles/inverse.h"
-#include "expressions/roles/not.h"
-#include "expressions/roles/or.h"
-#include "expressions/roles/primitive.h"
-#include "expressions/roles/restrict.h"
-#include "expressions/roles/top.h"
-#include "expressions/roles/transitive_closure.h"
-#include "expressions/roles/transitive_reflexive_closure.h"
-
-#include <algorithm>
-#include <stdexcept>
-
-
-namespace dlplan::core::parser {
-
-std::unique_ptr<Expression> ExpressionFactory::make_expression(const std::string& name, std::vector<std::unique_ptr<Expression>> &&children) {
-    if (name == EmptyBoolean::get_name()) {
-        return std::make_unique<EmptyBoolean>(name, std::move(children));
-    } else if (name == InclusionBoolean::get_name()) {
-        return std::make_unique<InclusionBoolean>(name, std::move(children));
-    } else if (name == NullaryBoolean::get_name()) {
-        return std::make_unique<NullaryBoolean>(name, std::move(children));
-    } else if (name == AllConcept::get_name()) {
-        return std::make_unique<AllConcept>(name, std::move(children));
-    } else if (name == AndConcept::get_name()) {
-        return std::make_unique<AndConcept>(name, std::move(children));
-    } else if (name == BotConcept::get_name()) {
-        return std::make_unique<BotConcept>(name, std::move(children));
-    } else if (name == DiffConcept::get_name()) {
-        return std::make_unique<DiffConcept>(name, std::move(children));
-    } else if (name == EqualConcept::get_name()) {
-        return std::make_unique<EqualConcept>(name, std::move(children));
-    } else if (name == NotConcept::get_name()) {
-        return std::make_unique<NotConcept>(name, std::move(children));
-    } else if (name == OneOfConcept::get_name()) {
-        return std::make_unique<OneOfConcept>(name, std::move(children));
-    } else if (name == OrConcept::get_name()) {
-        return std::make_unique<OrConcept>(name, std::move(children));
-    } else if (name == PrimitiveConcept::get_name()) {
-        return std::make_unique<PrimitiveConcept>(name, std::move(children));
-    } else if (name == ProjectionConcept::get_name()) {
-        return std::make_unique<ProjectionConcept>(name, std::move(children));
-    } else if (name == SomeConcept::get_name()) {
-        return std::make_unique<SomeConcept>(name, std::move(children));
-    } else if (name == SubsetConcept::get_name()) {
-        return std::make_unique<SubsetConcept>(name, std::move(children));
-    } else if (name == TopConcept::get_name()) {
-        return std::make_unique<TopConcept>(name, std::move(children));
-    } else if (name == ConceptDistanceNumerical::get_name()) {
-        return std::make_unique<ConceptDistanceNumerical>(name, std::move(children));
-    } else if (name == CountNumerical::get_name()) {
-        return std::make_unique<CountNumerical>(name, std::move(children));
-    } else if (name == RoleDistanceNumerical::get_name()) {
-        return std::make_unique<RoleDistanceNumerical>(name, std::move(children));
-    } else if (name == SumConceptDistanceNumerical::get_name()) {
-        return std::make_unique<SumConceptDistanceNumerical>(name, std::move(children));
-    } else if (name == SumRoleDistanceNumerical::get_name()) {
-        return std::make_unique<SumRoleDistanceNumerical>(name, std::move(children));
-    } else if (name == AndRole::get_name()) {
-        return std::make_unique<AndRole>(name, std::move(children));
-    } else if (name == ComposeRole::get_name()) {
-        return std::make_unique<ComposeRole>(name, std::move(children));
-    } else if (name == DiffRole::get_name()) {
-        return std::make_unique<DiffRole>(name, std::move(children));
-    } else if (name == IdentityRole::get_name()) {
-        return std::make_unique<IdentityRole>(name, std::move(children));
-    } else if (name == InverseRole::get_name()) {
-        return std::make_unique<InverseRole>(name, std::move(children));
-    } else if (name == NotRole::get_name()) {
-        return std::make_unique<NotRole>(name, std::move(children));
-    } else if (name == OrRole::get_name()) {
-        return std::make_unique<OrRole>(name, std::move(children));
-    } else if (name == PrimitiveRole::get_name()) {
-        return std::make_unique<PrimitiveRole>(name, std::move(children));
-    } else if (name == RestrictRole::get_name()) {
-        return std::make_unique<RestrictRole>(name, std::move(children));
-    } else if (name == TopRole::get_name()) {
-        return std::make_unique<TopRole>(name, std::move(children));
-    } else if (name == TransitiveClosureRole::get_name()) {
-        return std::make_unique<TransitiveClosureRole>(name, std::move(children));
-    } else if (name == TransitiveReflexiveClosureRole::get_name()) {
-        return std::make_unique<TransitiveReflexiveClosureRole>(name, std::move(children));
-    }
-    return std::make_unique<Expression>(name, std::move(children));
-}
-
-
-}
diff --git a/src/core/parser_old/expression_factory.h b/src/core/parser_old/expression_factory.h
deleted file mode 100644
index 0eab468b..00000000
--- a/src/core/parser_old/expression_factory.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_FACTORY_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_FACTORY_H_
-
-#include <vector>
-#include <memory>
-
-
-namespace dlplan::core {
-class VocabularyInfo;
-namespace parser {
-class Expression;
-
-class ExpressionFactory {
-public:
-    std::unique_ptr<Expression> make_expression(
-        const std::string& name,
-        std::vector<std::unique_ptr<Expression>> &&children);
-};
-
-}
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/boolean.h b/src/core/parser_old/expressions/boolean.h
deleted file mode 100644
index c54201cf..00000000
--- a/src/core/parser_old/expressions/boolean.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEAN_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEAN_H_
-
-#include "expression.h"
-#include "../../cache.h"
-
-
-namespace dlplan::core {
-class Boolean;
-}
-
-namespace dlplan::core::parser {
-
-class Boolean : public Expression {
-public:
-    Boolean(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Expression(name, std::move(children)) { }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/booleans/empty.h b/src/core/parser_old/expressions/booleans/empty.h
deleted file mode 100644
index e42f185a..00000000
--- a/src/core/parser_old/expressions/booleans/empty.h
+++ /dev/null
@@ -1,43 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEAN_EMPTY_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEAN_EMPTY_H_
-
-#include "../boolean.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class EmptyBoolean : public Boolean {
-private:
-    static inline const std::string m_name = "b_empty";
-
-public:
-    EmptyBoolean(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Boolean(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Boolean> parse_boolean(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("EmptyBoolean::parse_boolean - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse and construct children
-        auto concept_element = m_children[0]->parse_concept(factory);
-        if (concept_element) {
-            return factory.make_empty_boolean(concept_element);
-        }
-        auto role_element = m_children[0]->parse_role(factory);
-        if (role_element) {
-            return factory.make_empty_boolean(role_element);
-        }
-        // 2. If unsuccessful then throw a runtime error.
-        throw std::runtime_error("EmptyBoolean::parse_boolean - unable to construct children elements.");
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/booleans/inclusion.h b/src/core/parser_old/expressions/booleans/inclusion.h
deleted file mode 100644
index 7c4cbf53..00000000
--- a/src/core/parser_old/expressions/booleans/inclusion.h
+++ /dev/null
@@ -1,45 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEAN_INCLUSION_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEAN_INCLUSION_H_
-
-#include "../boolean.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class InclusionBoolean : public Boolean {
-private:
-    static inline const std::string m_name = "b_inclusion";
-
-public:
-    InclusionBoolean(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Boolean(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Boolean> parse_boolean(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("InclusionBoolean::parse_boolean - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse and construct children
-        auto concept_left = m_children[0]->parse_concept(factory);
-        auto concept_right = m_children[1]->parse_concept(factory);
-        if (concept_left && concept_right) {
-            return factory.make_inclusion_boolean(concept_left, concept_right);
-        }
-        auto role_left = m_children[0]->parse_role(factory);
-        auto role_right = m_children[1]->parse_role(factory);
-        if (role_left && role_right) {
-            return factory.make_inclusion_boolean(role_left, role_right);
-        }
-        // 2. If unsuccessful then throw a runtime error.
-        throw std::runtime_error("EmptyBoolean::parse_boolean - unable to construct children elements.");
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/booleans/nullary.h b/src/core/parser_old/expressions/booleans/nullary.h
deleted file mode 100644
index 9e3fe9d0..00000000
--- a/src/core/parser_old/expressions/booleans/nullary.h
+++ /dev/null
@@ -1,37 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEANS_NULLARY_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_BOOLEANS_NULLARY_H_
-
-#include "../boolean.h"
-
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class NullaryBoolean : public Boolean {
-private:
-    static inline const std::string m_name = "b_nullary";
-
-public:
-    NullaryBoolean(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Boolean(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Boolean> parse_boolean(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("NullaryBoolean::parse_boolean - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        const auto& predicate_name = m_children[0]->get_name();
-        // 2. Construct element
-        return factory.make_nullary_boolean(factory.get_vocabulary_info()->get_predicate(predicate_name));
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concept.h b/src/core/parser_old/expressions/concept.h
deleted file mode 100644
index 663069d8..00000000
--- a/src/core/parser_old/expressions/concept.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPT_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPT_H_
-
-#include "expression.h"
-#include "../../cache.h"
-
-
-namespace dlplan::core {
-class Concept;
-}
-
-namespace dlplan::core::parser {
-
-class Concept : public Expression {
-public:
-    Concept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Expression(name, std::move(children)) { }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/all.h b/src/core/parser_old/expressions/concepts/all.h
deleted file mode 100644
index 8ecc00fe..00000000
--- a/src/core/parser_old/expressions/concepts/all.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_ALL_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_ALL_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class AllConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_all";
-
-public:
-    AllConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("AllConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        auto concept = m_children[1]->parse_concept(factory);
-        if (!(role && concept)) {
-            throw std::runtime_error("AllConcept::parse_concept - at least one child is a nullptr");
-        }
-        // 2. Construct element
-        return factory.make_all_concept(role, concept);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/and.h b/src/core/parser_old/expressions/concepts/and.h
deleted file mode 100644
index bcf18476..00000000
--- a/src/core/parser_old/expressions/concepts/and.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_AND_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_AND_H_
-
-#include "../concept.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class AndConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_and";
-
-public:
-    AndConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, sort_children_lexicographically(std::move(children))) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("AndConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto concept_left = m_children[0]->parse_concept(factory);
-        auto concept_right = m_children[1]->parse_concept(factory);
-        if (!(concept_left && concept_right)) {
-            throw std::runtime_error("AndConcept::parse_concept - children are not of type Concept.");
-        }
-        // 2. Construct element
-        return factory.make_and_concept(concept_left, concept_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/bot.h b/src/core/parser_old/expressions/concepts/bot.h
deleted file mode 100644
index 2453c1ce..00000000
--- a/src/core/parser_old/expressions/concepts/bot.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_BOT_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_BOT_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class BotConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_bot";
-
-public:
-    BotConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 0) {
-            throw std::runtime_error("BotConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 0).");
-        }
-        // 2. Construct element
-        return factory.make_bot_concept();
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/diff.h b/src/core/parser_old/expressions/concepts/diff.h
deleted file mode 100644
index f0812c30..00000000
--- a/src/core/parser_old/expressions/concepts/diff.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_DIFF_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_DIFF_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class DiffConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_diff";
-
-public:
-    DiffConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("DiffConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto concept_left = m_children[0]->parse_concept(factory);
-        auto concept_right = m_children[1]->parse_concept(factory);
-        if (!(concept_left && concept_right)) {
-            throw std::runtime_error("DiffConcept::parse_concept - children are not of type Concept.");
-        }
-        // 2. Construct element
-        return factory.make_diff_concept(concept_left, concept_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/equal.h b/src/core/parser_old/expressions/concepts/equal.h
deleted file mode 100644
index e65712aa..00000000
--- a/src/core/parser_old/expressions/concepts/equal.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_EQUAL_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_EQUAL_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class EqualConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_equal";
-
-public:
-    EqualConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("EqualConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role_left = m_children[0]->parse_role(factory);
-        auto role_right = m_children[1]->parse_role(factory);
-        if (!(role_left && role_right)) {
-            throw std::runtime_error("EqualConcept::parse_concept - at least one children is a nullptr");
-        }
-        // 2. Construct element
-        return factory.make_equal_concept(role_left, role_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/not.h b/src/core/parser_old/expressions/concepts/not.h
deleted file mode 100644
index 343ec0d5..00000000
--- a/src/core/parser_old/expressions/concepts/not.h
+++ /dev/null
@@ -1,39 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_NOT_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_NOT_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class NotConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_not";
-
-public:
-    NotConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("NotConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto concept = m_children[0]->parse_concept(factory);
-        if (!concept) {
-            throw std::runtime_error("NotConcept::parse_concept - child is not of type Concept.");
-        }
-        // 2. Construct element
-        return factory.make_not_concept(concept);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/one_of.h b/src/core/parser_old/expressions/concepts/one_of.h
deleted file mode 100644
index 20bd12c7..00000000
--- a/src/core/parser_old/expressions/concepts/one_of.h
+++ /dev/null
@@ -1,35 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_ONE_OF_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_ONE_OF_H_
-
-#include "../concept.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class OneOfConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_one_of";
-
-public:
-    OneOfConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("OneOfConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        const auto& constant_name = m_children[0]->get_name();
-        return factory.make_one_of_concept(factory.get_vocabulary_info()->get_constant(constant_name));
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/or.h b/src/core/parser_old/expressions/concepts/or.h
deleted file mode 100644
index a5242506..00000000
--- a/src/core/parser_old/expressions/concepts/or.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_OR_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_OR_H_
-
-#include "../concept.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class OrConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_or";
-
-public:
-    OrConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, sort_children_lexicographically(std::move(children))) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("OrConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto concept_left = m_children[0]->parse_concept(factory);
-        auto concept_right = m_children[1]->parse_concept(factory);
-        if (!(concept_left && concept_right)) {
-            throw std::runtime_error("OrConcept::parse_concept - children are not of type Concept.");
-        }
-        // 2. Construct element
-        return factory.make_or_concept(concept_left, concept_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/primitive.h b/src/core/parser_old/expressions/concepts/primitive.h
deleted file mode 100644
index 65992b69..00000000
--- a/src/core/parser_old/expressions/concepts/primitive.h
+++ /dev/null
@@ -1,38 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_PRIMITIVE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_PRIMITIVE_H_
-
-#include "../concept.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class PrimitiveConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_primitive";
-
-public:
-    PrimitiveConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("PrimitiveConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        const auto& predicate_name = m_children[0]->get_name();
-        int pos = try_parse_number(m_children[1]->get_name());
-        // 2. Construct element
-        return factory.make_primitive_concept(factory.get_vocabulary_info()->get_predicate(predicate_name), pos);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/projection.h b/src/core/parser_old/expressions/concepts/projection.h
deleted file mode 100644
index 1efa86ce..00000000
--- a/src/core/parser_old/expressions/concepts/projection.h
+++ /dev/null
@@ -1,42 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_PROJECTION_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_PROJECTION_H_
-
-#include "../concept.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class ProjectionConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_projection";
-
-public:
-    ProjectionConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("ProjectionConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        auto role = m_children[0]->parse_role(factory);
-        if (!role) {
-            throw std::runtime_error("ProjectionConcept::parse_concept - child is a nullptr.");
-        }
-        int pos = try_parse_number(m_children[1]->get_name());
-        if (pos < 0 || pos > 1) {
-            throw std::runtime_error("ProjectionConcept::parse_concept - projection index out of range, should be 0 or 1 ("s + std::to_string(pos) + ")");
-        }
-        return factory.make_projection_concept(role, pos);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/some.h b/src/core/parser_old/expressions/concepts/some.h
deleted file mode 100644
index 1dea2b41..00000000
--- a/src/core/parser_old/expressions/concepts/some.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_SOME_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_SOME_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class SomeConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_some";
-
-public:
-    SomeConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("SomeConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        auto concept = m_children[1]->parse_concept(factory);
-        if (!(role && concept)) {
-            throw std::runtime_error("SomeConcept::parse_concept - at least one children is a nullptr");
-        }
-        // 2. Construct element
-        return factory.make_some_concept(role, concept);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/subset.h b/src/core/parser_old/expressions/concepts/subset.h
deleted file mode 100644
index 8c599e7c..00000000
--- a/src/core/parser_old/expressions/concepts/subset.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_SUBSET_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_SUBSET_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class SubsetConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_subset";
-
-public:
-    SubsetConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("SubsetConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role_left = m_children[0]->parse_role(factory);
-        auto role_right = m_children[1]->parse_role(factory);
-        if (!(role_left && role_right)) {
-            throw std::runtime_error("SubsetConcept::parse_concept - at least one children is a nullptr");
-        }
-        // 2. Construct element
-        return factory.make_subset_concept(role_left, role_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/concepts/top.h b/src/core/parser_old/expressions/concepts/top.h
deleted file mode 100644
index be437e9e..00000000
--- a/src/core/parser_old/expressions/concepts/top.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_TOP_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_CONCEPTS_TOP_H_
-
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class TopConcept : public Concept {
-private:
-    static inline const std::string m_name = "c_top";
-
-public:
-    TopConcept(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Concept(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Concept> parse_concept(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 0) {
-            throw std::runtime_error("TopConcept::parse_concept - number of children ("s + std::to_string(m_children.size()) + " != 0).");
-        }
-        // 2. Construct element
-        return factory.make_top_concept();
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/expression.h b/src/core/parser_old/expressions/expression.h
deleted file mode 100644
index 4f11da90..00000000
--- a/src/core/parser_old/expressions/expression.h
+++ /dev/null
@@ -1,97 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_EXPRESSION_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_EXPRESSION_H_
-
-#include <sstream>
-#include <string>
-#include <vector>
-#include <memory>
-
-
-namespace dlplan::core {
-class VocabularyInfo;
-struct Caches;
-class Concept;
-class Role;
-class Boolean;
-class Numerical;
-class SyntacticElementFactory;
-}
-
-namespace dlplan::core::parser {
-
-/**
- * An Expression represents a node in an abstract syntax tree.
- */
-class Expression {
-protected:
-    std::string m_name;
-    std::vector<std::unique_ptr<Expression>> m_children;
-
-public:
-    Expression(const std::string &name,
-        std::vector<std::unique_ptr<Expression>> &&children)
-        : m_name(name), m_children(std::move(children)) {
-    }
-    virtual ~Expression() = default;
-
-    /**
-     * Returns true if the expression is a leaf, i.e.,
-     * an expression that represents a position in a predicate for projection.
-     */
-    bool is_leaf() const {
-        return m_children.empty();
-    }
-
-    /**
-     * Getters.
-     */
-    const std::string& get_name() const {
-        return m_name;
-    }
-
-    // Note: since children are stored as std::vector<Expression>
-    // we do not know what type the children will be
-    // and each concrete type must decide what method to call
-    // in order to parse into the desired type.
-    // As a result we cannot change this into a template.
-
-    /**
-     * Tries to parse the Expression into a Concept.
-     * If unsuccessful print human readable error messages and throw and exception.
-     */
-    virtual std::shared_ptr<const dlplan::core::Concept>
-    parse_concept(dlplan::core::SyntacticElementFactory& /* factory */ ) const {
-        return nullptr;
-    }
-
-    /**
-     * Tries to parse the Expression into a Role.
-     * If unsuccessful print human readable error messages and throw and exception.
-     */
-    virtual std::shared_ptr<const dlplan::core::Role>
-    parse_role(dlplan::core::SyntacticElementFactory& /* factory */ ) const {
-        return nullptr;
-    }
-
-    /**
-     * Tries to parse the Expression into a Numerical.
-     * If unsuccessful print human readable error messages and throw and exception.
-     */
-    virtual std::shared_ptr<const dlplan::core::Numerical>
-    parse_numerical(dlplan::core::SyntacticElementFactory& /* factory */ ) const {
-        return nullptr;
-    }
-
-    /**
-     * Tries to parse the Expression into a Boolean.
-     * If unsuccessful print human readable error messages and throw and exception.
-     */
-    virtual std::shared_ptr<const dlplan::core::Boolean>
-    parse_boolean(dlplan::core::SyntacticElementFactory& /* factory */ ) const {
-        return nullptr;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/numerical.h b/src/core/parser_old/expressions/numerical.h
deleted file mode 100644
index 6ca340ee..00000000
--- a/src/core/parser_old/expressions/numerical.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_H_
-
-#include "expression.h"
-#include "../../cache.h"
-
-
-namespace dlplan::core {
-class Numerical;
-}
-
-
-namespace dlplan::core::parser {
-
-class Numerical : public Expression {
-public:
-    Numerical(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Expression(name, std::move(children)) { }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/numericals/concept_distance.h b/src/core/parser_old/expressions/numericals/concept_distance.h
deleted file mode 100644
index f519bdb8..00000000
--- a/src/core/parser_old/expressions/numericals/concept_distance.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_CONCEPT_DISTANCE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_CONCEPT_DISTANCE_H_
-
-#include "../numerical.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class ConceptDistanceNumerical : public Numerical {
-private:
-    static inline const std::string m_name = "n_concept_distance";
-
-public:
-    ConceptDistanceNumerical(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Numerical(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Numerical> parse_numerical(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 3) {
-            throw std::runtime_error("ConceptDistanceNumerical::parse_numerical - number of children ("s + std::to_string(m_children.size()) + " != 3).");
-        }
-        // 1. Parse children
-        auto concept_from = m_children[0]->parse_concept(factory);
-        auto role = m_children[1]->parse_role(factory);
-        auto concept_to = m_children[2]->parse_concept(factory);
-        if (!(concept_from && role && concept_to)) {
-            throw std::runtime_error("ConceptDistanceNumerical::parse_numerical - child is not of type Concept, Role, Concept.");
-        }
-        return factory.make_concept_distance_numerical(concept_from, role, concept_to);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/numericals/count.h b/src/core/parser_old/expressions/numericals/count.h
deleted file mode 100644
index d9a7e5fb..00000000
--- a/src/core/parser_old/expressions/numericals/count.h
+++ /dev/null
@@ -1,43 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_COUNT_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_COUNT_H_
-
-#include "../numerical.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class CountNumerical : public Numerical {
-private:
-    static inline const std::string m_name = "n_count";
-
-public:
-    CountNumerical(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Numerical(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Numerical> parse_numerical(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("CountNumerical::parse_numerical - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto concept = m_children[0]->parse_concept(factory);
-        if (concept) {
-            return factory.make_count_numerical(concept);
-        }
-        auto role = m_children[0]->parse_role(factory);
-        if (role) {
-            return factory.make_count_numerical(role);
-        }
-        // 2. Construct element
-        throw std::runtime_error("CountNumerical::parse_numerical - unable to construct children elements.");
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/numericals/role_distance.h b/src/core/parser_old/expressions/numericals/role_distance.h
deleted file mode 100644
index 285417e9..00000000
--- a/src/core/parser_old/expressions/numericals/role_distance.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_ROLE_DISTANCE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_ROLE_DISTANCE_H_
-
-#include "../numerical.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class RoleDistanceNumerical : public Numerical {
-private:
-    static inline const std::string m_name = "n_role_distance";
-
-public:
-    RoleDistanceNumerical(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Numerical(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Numerical> parse_numerical(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 3) {
-            throw std::runtime_error("RoleDistanceNumerical::parse_numerical - number of children ("s + std::to_string(m_children.size()) + " != 3).");
-        }
-        // 1. Parse children
-        auto role_from = m_children[0]->parse_role(factory);
-        auto role = m_children[1]->parse_role(factory);
-        auto role_to = m_children[2]->parse_role(factory);
-        if (!(role_from && role && role_to)) {
-            throw std::runtime_error("RoleDistanceNumerical::parse_numerical - child is not of type Role, Role, Role.");
-        }
-        return factory.make_role_distance_numerical(role_from, role, role_to);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/numericals/sum_concept_distance.h b/src/core/parser_old/expressions/numericals/sum_concept_distance.h
deleted file mode 100644
index 889b5a9c..00000000
--- a/src/core/parser_old/expressions/numericals/sum_concept_distance.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_SUM_CONCEPT_DISTANCE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_SUM_CONCEPT_DISTANCE_H_
-
-#include "../numerical.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class SumConceptDistanceNumerical : public Numerical {
-private:
-    static inline const std::string m_name = "n_sum_concept_distance";
-
-public:
-    SumConceptDistanceNumerical(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Numerical(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Numerical> parse_numerical(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 3) {
-            throw std::runtime_error("SumConceptDistanceNumerical::parse_numerical - number of children ("s + std::to_string(m_children.size()) + " != 3).");
-        }
-        // 1. Parse children
-        auto concept_from = m_children[0]->parse_concept(factory);
-        auto role = m_children[1]->parse_role(factory);
-        auto concept_to = m_children[2]->parse_concept(factory);
-        if (!(concept_from && role && concept_to)) {
-            throw std::runtime_error("SumConceptDistanceNumerical::parse_numerical - child is not of type Concept, Role, Concept.");
-        }
-        return factory.make_sum_concept_distance_numerical(concept_from, role, concept_to);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/numericals/sum_role_distance.h b/src/core/parser_old/expressions/numericals/sum_role_distance.h
deleted file mode 100644
index 91320bf7..00000000
--- a/src/core/parser_old/expressions/numericals/sum_role_distance.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_SUM_ROLE_DISTANCE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_NUMERICAL_SUM_ROLE_DISTANCE_H_
-
-#include "../numerical.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class SumRoleDistanceNumerical : public Numerical {
-private:
-    static inline const std::string m_name = "n_sum_role_distance";
-
-public:
-    SumRoleDistanceNumerical(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Numerical(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Numerical> parse_numerical(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 3) {
-            throw std::runtime_error("SumRoleDistanceNumerical::parse_numerical - number of children ("s + std::to_string(m_children.size()) + " != 3).");
-        }
-        // 1. Parse children
-        auto role_from = m_children[0]->parse_role(factory);
-        auto role = m_children[1]->parse_role(factory);
-        auto role_to = m_children[2]->parse_role(factory);
-        if (!(role_from && role && role_to)) {
-            throw std::runtime_error("SumRoleDistanceNumerical::parse_numerical - child is not of type Role, Role, Role.");
-        }
-        return factory.make_sum_role_distance_numerical(role_from, role, role_to);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/role.h b/src/core/parser_old/expressions/role.h
deleted file mode 100644
index a75286ce..00000000
--- a/src/core/parser_old/expressions/role.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLE_H_
-
-#include "expression.h"
-#include "../../cache.h"
-
-
-namespace dlplan::core {
-class Role;
-}
-
-
-namespace dlplan::core::parser {
-
-class Role : public Expression {
-public:
-    Role(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Expression(name, std::move(children)) { }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/and.h b/src/core/parser_old/expressions/roles/and.h
deleted file mode 100644
index d9011c9d..00000000
--- a/src/core/parser_old/expressions/roles/and.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_AND_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_AND_H_
-
-#include "../role.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class AndRole : public Role {
-private:
-    static inline const std::string m_name = "r_and";
-
-public:
-    AndRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, sort_children_lexicographically(std::move(children))) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("AndRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role_left = m_children[0]->parse_role(factory);
-        auto role_right = m_children[1]->parse_role(factory);
-        if (!(role_left && role_right)) {
-            throw std::runtime_error("AndRole::parse_role - children are not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_and_role(role_left, role_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/compose.h b/src/core/parser_old/expressions/roles/compose.h
deleted file mode 100644
index 4c014acb..00000000
--- a/src/core/parser_old/expressions/roles/compose.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_COMPOSE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_COMPOSE_H_
-
-#include "../role.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class ComposeRole : public Role {
-private:
-    static inline const std::string m_name = "r_compose";
-
-public:
-    ComposeRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("ComposeRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role_left = m_children[0]->parse_role(factory);
-        auto role_right = m_children[1]->parse_role(factory);
-        if (!(role_left && role_right)) {
-            throw std::runtime_error("ComposeRole::parse_role - children are not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_compose_role(role_left, role_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/diff.h b/src/core/parser_old/expressions/roles/diff.h
deleted file mode 100644
index a37f52c7..00000000
--- a/src/core/parser_old/expressions/roles/diff.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_DIFF_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_DIFF_H_
-
-#include "../role.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class DiffRole : public Role {
-private:
-    static inline const std::string m_name = "r_diff";
-
-public:
-    DiffRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("DiffRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role_left = m_children[0]->parse_role(factory);
-        auto role_right = m_children[1]->parse_role(factory);
-        if (!(role_left && role_right)) {
-            throw std::runtime_error("DiffRole::parse_role - children are not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_diff_role(role_left, role_right);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/identity.h b/src/core/parser_old/expressions/roles/identity.h
deleted file mode 100644
index 1ad71ba1..00000000
--- a/src/core/parser_old/expressions/roles/identity.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_IDENTITY_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_IDENTITY_H_
-
-#include "../role.h"
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class IdentityRole : public Role {
-private:
-    static inline const std::string m_name = "r_identity";
-
-public:
-    IdentityRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("IdentityRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto concept = m_children[0]->parse_concept(factory);
-        if (!concept) {
-            throw std::runtime_error("IdentityRole::parse_role - child is not of type concept");
-        }
-        // 2. Construct element
-        return factory.make_identity_role(concept);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/inverse.h b/src/core/parser_old/expressions/roles/inverse.h
deleted file mode 100644
index 663bf75a..00000000
--- a/src/core/parser_old/expressions/roles/inverse.h
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_INVERSE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_INVERSE_H_
-
-#include "../role.h"
-#include "../concept.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class InverseRole : public Role {
-private:
-    static inline const std::string m_name = "r_inverse";
-
-public:
-    InverseRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("InverseRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        if (!role) {
-            throw std::runtime_error("InverseRole::parse_role - child is not of type role");
-        }
-        // 2. Construct element
-        return factory.make_inverse_role(role);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/not.h b/src/core/parser_old/expressions/roles/not.h
deleted file mode 100644
index 77699f63..00000000
--- a/src/core/parser_old/expressions/roles/not.h
+++ /dev/null
@@ -1,39 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_NOT_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_NOT_H_
-
-#include "../role.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class NotRole : public Role {
-private:
-    static inline const std::string m_name = "r_not";
-
-public:
-    NotRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("NotRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        if (!role) {
-            throw std::runtime_error("NotRole::parse_role - child is not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_not_role(role);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/or.h b/src/core/parser_old/expressions/roles/or.h
deleted file mode 100644
index 530d87dd..00000000
--- a/src/core/parser_old/expressions/roles/or.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_OR_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_OR_H_
-
-#include "../role.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class OrRole : public Role {
-private:
-    static inline const std::string m_name = "r_or";
-
-public:
-    OrRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, sort_children_lexicographically(std::move(children))) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("OrRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto left_role = m_children[0]->parse_role(factory);
-        auto right_role = m_children[1]->parse_role(factory);
-        if (!(left_role && right_role)) {
-            throw std::runtime_error("OrRole::parse_role - children are not of type Concept.");
-        }
-        // 2. Construct element
-        return factory.make_or_role(left_role, right_role);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/primitive.h b/src/core/parser_old/expressions/roles/primitive.h
deleted file mode 100644
index 37e4e04e..00000000
--- a/src/core/parser_old/expressions/roles/primitive.h
+++ /dev/null
@@ -1,39 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_PRIMITIVE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_PRIMITIVE_H_
-
-#include "../role.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class PrimitiveRole : public Role {
-private:
-    static inline const std::string m_name = "r_primitive";
-
-public:
-    PrimitiveRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 3) {
-            throw std::runtime_error("PrimitiveRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 3).");
-        }
-        // 1. Parse children
-        const auto& predicate_name = m_children[0]->get_name();
-        int pos_1 = try_parse_number(m_children[1]->get_name());
-        int pos_2 = try_parse_number(m_children[2]->get_name());
-        // 2. Construct element
-        return factory.make_primitive_role(factory.get_vocabulary_info()->get_predicate(predicate_name), pos_1, pos_2);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/restrict.h b/src/core/parser_old/expressions/roles/restrict.h
deleted file mode 100644
index bb1474fb..00000000
--- a/src/core/parser_old/expressions/roles/restrict.h
+++ /dev/null
@@ -1,42 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_RESTRICT_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_RESTRICT_H_
-
-#include "../role.h"
-#include "../concept.h"
-#include "../../utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class RestrictRole : public Role {
-private:
-    static inline const std::string m_name = "r_restrict";
-
-public:
-    RestrictRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 2) {
-            throw std::runtime_error("RestrictRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 2).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        auto concept = m_children[1]->parse_concept(factory);
-        if (!(role && concept)) {
-            throw std::runtime_error("RestrictRole::parse_role - children are not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_restrict_role(role, concept);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/top.h b/src/core/parser_old/expressions/roles/top.h
deleted file mode 100644
index 35a06063..00000000
--- a/src/core/parser_old/expressions/roles/top.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_TOP_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_TOP_H_
-
-#include "../role.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class TopRole : public Role {
-private:
-    static inline const std::string m_name = "r_top";
-
-public:
-    TopRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 0) {
-            throw std::runtime_error("TopRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 0).");
-        }
-        // 2. Construct element
-        return factory.make_top_role();
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/transitive_closure.h b/src/core/parser_old/expressions/roles/transitive_closure.h
deleted file mode 100644
index 80af1ecb..00000000
--- a/src/core/parser_old/expressions/roles/transitive_closure.h
+++ /dev/null
@@ -1,39 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_TRANSITIVE_CLOSURE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_TRANSITIVE_CLOSURE_H_
-
-#include "../role.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class TransitiveClosureRole : public Role {
-private:
-    static inline const std::string m_name = "r_transitive_closure";
-
-public:
-    TransitiveClosureRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("TransitiveClosureRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        if (!role) {
-            throw std::runtime_error("TransitiveClosureRole::parse_role - child is not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_transitive_closure(role);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/expressions/roles/transitive_reflexive_closure.h b/src/core/parser_old/expressions/roles/transitive_reflexive_closure.h
deleted file mode 100644
index 72131334..00000000
--- a/src/core/parser_old/expressions/roles/transitive_reflexive_closure.h
+++ /dev/null
@@ -1,39 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_TRANSITIVE_REFLEXIVE_CLOSURE_H_
-#define DLPLAN_SRC_CORE_PARSER_EXPRESSIONS_ROLES_TRANSITIVE_REFLEXIVE_CLOSURE_H_
-
-#include "../role.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-
-class TransitiveReflexiveClosureRole : public Role {
-private:
-    static inline const std::string m_name = "r_transitive_reflexive_closure";
-
-public:
-    TransitiveReflexiveClosureRole(const std::string &name, std::vector<std::unique_ptr<Expression>> &&children)
-    : Role(name, std::move(children)) { }
-
-    std::shared_ptr<const dlplan::core::Role> parse_role(SyntacticElementFactory& factory) const override {
-        if (m_children.size() != 1) {
-            throw std::runtime_error("TransitiveReflexiveClosureRole::parse_role - number of children ("s + std::to_string(m_children.size()) + " != 1).");
-        }
-        // 1. Parse children
-        auto role = m_children[0]->parse_role(factory);
-        if (!role) {
-            throw std::runtime_error("TransitiveReflexiveClosureRole::parse_role - child is not of type Role.");
-        }
-        // 2. Construct element
-        return factory.make_transitive_reflexive_closure(role);
-    }
-
-    static const std::string& get_name() {
-        return m_name;
-    }
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/parser.cpp b/src/core/parser_old/parser.cpp
deleted file mode 100644
index 6e99c01c..00000000
--- a/src/core/parser_old/parser.cpp
+++ /dev/null
@@ -1,60 +0,0 @@
-#include "parser.h"
-
-#include "expressions/expression.h"
-#include "expression_factory.h"
-
-#include <vector>
-#include <exception>
-
-
-namespace dlplan::core::parser {
-static TokenRegexes element_token_regexes = {
-    { TokenType::COMMA, Tokenizer::build_regex(",") },
-    { TokenType::OPENING_PARENTHESIS, Tokenizer::build_regex("\\(") },
-    { TokenType::CLOSING_PARENTHESIS, Tokenizer::build_regex("\\)") },
-    { TokenType::NAME, Tokenizer::build_regex("[a-zA-Z0-9_\\-]+") },
-};
-
-
-/**
- * Parses the canonical AST from the given tokens.
- * Tokens in children are sorted lexicographically.
- */
-std::unique_ptr<Expression> Parser::parse_expressions_tree(Tokens &tokens) const {
-    if (tokens.empty()) {
-        throw std::runtime_error("Parser::parse_expressions_tree - Unexpected EOF\n");
-    }
-    Token token = tokens.front();
-    tokens.pop_front();
-    // std::cout << token.first << " " << token.second << std::endl;
-    if (!tokens.empty() && tokens.front().first == TokenType::OPENING_PARENTHESIS) {
-        // Consume "(".
-        tokens.pop_front();
-        std::vector<std::unique_ptr<Expression>> children;
-        while (!tokens.empty() && tokens.front().first != TokenType::CLOSING_PARENTHESIS) {
-            if (tokens.front().first == TokenType::COMMA) {
-                tokens.pop_front();
-            }
-            children.push_back(parse_expressions_tree(tokens));
-        }
-        // Consume ")".
-        if (tokens.empty()) throw std::runtime_error("Parser::parse_expressions_tree - Expected ')' is missing.");
-        tokens.pop_front();
-        // Construct an expression that can be parsed into an element if the description is correct.
-        return ExpressionFactory().make_expression(token.second, std::move(children));
-    } else if (token.first == TokenType::CLOSING_PARENTHESIS) {
-        throw std::runtime_error("Parser::parse_expressions_tree - Unexpected ')'");
-    } else {
-        return ExpressionFactory().make_expression(token.second, {});
-    }
-}
-
-Parser::Parser() = default;
-
-std::unique_ptr<Expression> Parser::parse(
-    const std::string &description) const {
-    Tokens tokens = Tokenizer().tokenize(description, element_token_regexes);
-    return parse_expressions_tree(tokens);
-}
-
-}
diff --git a/src/core/parser_old/parser.h b/src/core/parser_old/parser.h
deleted file mode 100644
index 8cfa5798..00000000
--- a/src/core/parser_old/parser.h
+++ /dev/null
@@ -1,42 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_PARSER_H_
-#define DLPLAN_SRC_CORE_PARSER_PARSER_H_
-
-#include "../../utils/tokenizer.h"
-
-#include <string>
-
-
-namespace dlplan::core::parser {
-class Expression;
-
-enum class TokenType {
-    COMMA,
-    OPENING_PARENTHESIS,
-    CLOSING_PARENTHESIS,
-    NAME
-};
-
-using Token = dlplan::utils::Tokenizer<TokenType>::Token;
-using Tokens = dlplan::utils::Tokenizer<TokenType>::Tokens;
-using Tokenizer = dlplan::utils::Tokenizer<TokenType>;
-using TokenRegexes = dlplan::utils::Tokenizer<TokenType>::TokenRegexes;
-
-class Parser {
-private:
-    /**
-     * Parses tokens into an abstract syntax tree.
-     */
-    std::unique_ptr<Expression> parse_expressions_tree(Tokens &tokens) const;
-
-public:
-    Parser();
-
-    /**
-     * Parses a textual description into an abstract syntax tree.
-     */
-    std::unique_ptr<Expression> parse(const std::string &description) const;
-};
-
-}
-
-#endif
diff --git a/src/core/parser_old/utils.cpp b/src/core/parser_old/utils.cpp
deleted file mode 100644
index a225270b..00000000
--- a/src/core/parser_old/utils.cpp
+++ /dev/null
@@ -1,31 +0,0 @@
-#include "utils.h"
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-int try_parse_number(const std::string& name) {
-    if (!std::all_of(name.begin(), name.end(), [](char c){ return isdigit(c); })) {
-        throw std::runtime_error("try_parse_number - error parsing ("s + name + ") to int.");
-    }
-    return atoi(name.c_str());
-}
-
-
-bool is_number(const std::string& name) {
-    return std::all_of(name.begin(), name.end(), [](char c){ return isdigit(c); });
-}
-
-/**
- * Sort child expressions lexicographically.
- * We apply this in commutative expressions
- * to obtain a canonical representation.
- */
-std::vector<std::unique_ptr<Expression>> sort_children_lexicographically(std::vector<std::unique_ptr<Expression>> &&children) {
-    std::sort(children.begin(), children.end(),
-        [](const std::unique_ptr<Expression> &l, const std::unique_ptr<Expression> &r){ return l->get_name() < r->get_name(); });
-    return std::move(children);
-}
-
-
-}
diff --git a/src/core/parser_old/utils.h b/src/core/parser_old/utils.h
deleted file mode 100644
index f77a2d13..00000000
--- a/src/core/parser_old/utils.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#ifndef DLPLAN_SRC_CORE_PARSER_UTILS_H_
-#define DLPLAN_SRC_CORE_PARSER_UTILS_H_
-
-#include "expressions/expression.h"
-
-#include <algorithm>
-#include <vector>
-#include <string>
-#include <stdexcept>
-#include <memory>
-
-using namespace std::string_literals;
-
-
-namespace dlplan::core::parser {
-extern int try_parse_number(const std::string& name);
-
-extern bool is_number(const std::string& name);
-
-/**
- * Sort child expressions lexicographically.
- * We apply this in commutative expressions
- * to obtain a canonical representation.
- */
-extern std::vector<std::unique_ptr<Expression>> sort_children_lexicographically(std::vector<std::unique_ptr<Expression>> &&children);
-
-}
-
-#endif