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Code Issues 15 Releases 21 Activity

Made substitution of variables with terms fully recursive.

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This commit is contained in:
Patrick Lühne 2017-03-23 01:00:54 +01:00
parent 825cd4de39
commit 13ed0b013a
Signed by: patrick
GPG Key ID: 05F3611E97A70ABF
1 changed files with 69 additions and 50 deletions
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119
src/anthem/Simplification.cpp
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@ -19,77 +19,88 @@ bool isPrimitiveTerm(const ast::Term &term)
template<class T>
struct RecursiveFormulaVisitor
{
void visit(ast::And &and_, ast::Formula &formula)
template <class... Arguments>
void visit(ast::And &and_, ast::Formula &formula, Arguments &&... arguments)
{
for (auto &argument : and_.arguments)
argument.accept(*this, argument);
argument.accept(*this, argument, std::forward<Arguments>(arguments)...);
return T::accept(and_, formula);
return T::accept(and_, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Biconditional &biconditional, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Biconditional &biconditional, ast::Formula &formula, Arguments &&... arguments)
{
biconditional.left.accept(*this, biconditional.left);
biconditional.right.accept(*this, biconditional.right);
biconditional.left.accept(*this, biconditional.left, std::forward<Arguments>(arguments)...);
biconditional.right.accept(*this, biconditional.right, std::forward<Arguments>(arguments)...);
return T::accept(biconditional, formula);
return T::accept(biconditional, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Boolean &boolean, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Boolean &boolean, ast::Formula &formula, Arguments &&... arguments)
{
return T::accept(boolean, formula);
return T::accept(boolean, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Comparison &comparison, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Comparison &comparison, ast::Formula &formula, Arguments &&... arguments)
{
return T::accept(comparison, formula);
return T::accept(comparison, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Exists &exists, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Exists &exists, ast::Formula &formula, Arguments &&... arguments)
{
exists.argument.accept(*this, exists.argument);
exists.argument.accept(*this, exists.argument, std::forward<Arguments>(arguments)...);
return T::accept(exists, formula);
return T::accept(exists, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::ForAll &forAll, ast::Formula &formula)
template <class... Arguments>
void visit(ast::ForAll &forAll, ast::Formula &formula, Arguments &&... arguments)
{
forAll.argument.accept(*this, forAll.argument);
forAll.argument.accept(*this, forAll.argument, std::forward<Arguments>(arguments)...);
return T::accept(forAll, formula);
return T::accept(forAll, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Implies &implies, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Implies &implies, ast::Formula &formula, Arguments &&... arguments)
{
implies.antecedent.accept(*this, implies.antecedent);
implies.consequent.accept(*this, implies.consequent);
implies.antecedent.accept(*this, implies.antecedent, std::forward<Arguments>(arguments)...);
implies.consequent.accept(*this, implies.consequent, std::forward<Arguments>(arguments)...);
return T::accept(implies, formula);
return T::accept(implies, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::In &in, ast::Formula &formula)
template <class... Arguments>
void visit(ast::In &in, ast::Formula &formula, Arguments &&... arguments)
{
return T::accept(in, formula);
return T::accept(in, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Not &not_, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Not &not_, ast::Formula &formula, Arguments &&... arguments)
{
not_.argument.accept(*this, not_.argument);
not_.argument.accept(*this, not_.argument, std::forward<Arguments>(arguments)...);
return T::accept(not_, formula);
return T::accept(not_, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Or &or_, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Or &or_, ast::Formula &formula, Arguments &&... arguments)
{
for (auto &argument : or_.arguments)
argument.accept(*this, argument);
argument.accept(*this, argument, std::forward<Arguments>(arguments)...);
return T::accept(or_, formula);
return T::accept(or_, formula, std::forward<Arguments>(arguments)...);
}
void visit(ast::Predicate &predicate, ast::Formula &formula)
template <class... Arguments>
void visit(ast::Predicate &predicate, ast::Formula &formula, Arguments &&... arguments)
{
return T::accept(predicate, formula);
return T::accept(predicate, formula, std::forward<Arguments>(arguments)...);
}
};
@ -128,6 +139,28 @@ std::experimental::optional<ast::Term> extractAssignedTerm(ast::Formula &formula
////////////////////////////////////////////////////////////////////////////////////////////////////
struct ReplaceVariableWithTermVisitor : public RecursiveFormulaVisitor<ReplaceVariableWithTermVisitor>
{
static void accept(ast::Predicate &predicate, ast::Formula &, const ast::Variable &variable, ast::Term &&term)
{
for (auto &argument : predicate.arguments)
{
if (!matchesVariable(argument, variable))
continue;
argument = std::move(term);
return;
}
}
template<class T>
static void accept(T &, ast::Formula &, const ast::Variable &, ast::Term &&)
{
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////
void simplify(ast::Exists &exists, ast::Formula &formula)
{
if (!exists.argument.is<ast::And>())
@ -137,22 +170,9 @@ void simplify(ast::Exists &exists, ast::Formula &formula)
auto &arguments = conjunction.arguments;
// Check that formula is in normal form
if (!arguments.back().is<ast::Predicate>())
if (!arguments.back().is<ast::Predicate>() && !arguments.back().is<ast::Not>())
return;
const auto replaceVariableInPredicateWithTerm =
[](ast::Predicate &predicate, const ast::Variable &variable, ast::Term &term)
{
for (auto &argument : predicate.arguments)
{
if (!matchesVariable(argument, variable))
continue;
argument = std::move(term);
break;
}
};
// Simplify formulas of type “exists X (X = t and F(Y))” to “F(t)”
for (auto i = exists.variables.begin(); i != exists.variables.end();)
{
@ -168,10 +188,8 @@ void simplify(ast::Exists &exists, ast::Formula &formula)
if (!assignedTerm)
continue;
auto &lastArgument = arguments.back().get<ast::Predicate>();
// If this argument is an assignment of the variable to some other term, remove the assignment and replace the variable with the other term
replaceVariableInPredicateWithTerm(lastArgument, variable, assignedTerm.value());
arguments.back().accept(ReplaceVariableWithTermVisitor(), arguments.back(), variable, std::move(assignedTerm.value()));
arguments.erase(j);
wasVariableReplaced = true;
@ -196,8 +214,9 @@ void simplify(ast::Exists &exists, ast::Formula &formula)
// If the argument is a conjunction with just one element, directly replace the input formula with the argument
if (conjunction.arguments.size() == 1)
{
auto test = std::move(conjunction.arguments.front());
formula = std::move(test);
// TODO: remove workaround
auto tmp = std::move(conjunction.arguments.front());
formula = std::move(tmp);
return;
}