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Add simplification rule

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This commit is contained in:
Patrick Lühne 2020-06-05 18:58:14 +02:00
parent b29422cfbf
commit 6ca579735b
Signed by: patrick
GPG Key ID: 05F3611E97A70ABF
1 changed files with 86 additions and 0 deletions
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86
src/simplify.rs
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@ -196,6 +196,90 @@ fn simplify_quantified_formulas_without_parameters(formula: &mut crate::Formula)
}
}
fn join_nested_quantified_formulas_of_same_type(formula: &mut crate::Formula)
-> SimplificationResult
{
use crate::Formula;
match formula
{
Formula::And(arguments)
| Formula::IfAndOnlyIf(arguments)
| Formula::Or(arguments) =>
{
let mut simplification_result = SimplificationResult::NotSimplified;
for mut argument in arguments
{
simplification_result = simplification_result.or(
join_nested_quantified_formulas_of_same_type(&mut argument));
}
simplification_result
},
Formula::Boolean(_)
| Formula::Compare(_)
| Formula::Predicate(_) => SimplificationResult::NotSimplified,
Formula::Exists(ref mut quantified_formula) =>
{
let mut simplification_result =
join_nested_quantified_formulas_of_same_type(&mut quantified_formula.argument);
if let Formula::Exists(ref mut nested_quantified_formula) = *quantified_formula.argument
{
// TODO: remove workaround
let mut argument = crate::Formula::false_();
std::mem::swap(&mut argument, &mut nested_quantified_formula.argument);
let joined_parameters =
[&quantified_formula.parameters[..], &nested_quantified_formula.parameters[..]]
.concat()
.iter()
.map(|x| std::rc::Rc::clone(x))
.collect::<Vec<_>>();
quantified_formula.parameters = std::rc::Rc::new(joined_parameters);
*quantified_formula.argument = argument;
simplification_result = SimplificationResult::Simplified;
}
simplification_result
},
Formula::ForAll(ref mut quantified_formula) =>
{
let mut simplification_result =
join_nested_quantified_formulas_of_same_type(&mut quantified_formula.argument);
if let Formula::ForAll(ref mut nested_quantified_formula) = *quantified_formula.argument
{
// TODO: remove workaround
let mut argument = crate::Formula::false_();
std::mem::swap(&mut argument, &mut nested_quantified_formula.argument);
let joined_parameters =
[&quantified_formula.parameters[..], &nested_quantified_formula.parameters[..]]
.concat()
.iter()
.map(|x| std::rc::Rc::clone(x))
.collect::<Vec<_>>();
quantified_formula.parameters = std::rc::Rc::new(joined_parameters);
*quantified_formula.argument = argument;
simplification_result = SimplificationResult::Simplified;
}
simplification_result
},
Formula::Implies(ref mut implies) =>
join_nested_quantified_formulas_of_same_type(&mut implies.antecedent)
.or(join_nested_quantified_formulas_of_same_type(&mut implies.implication)),
Formula::Not(ref mut argument) =>
join_nested_quantified_formulas_of_same_type(argument),
}
}
fn simplify_trivial_n_ary_formulas(formula: &mut crate::Formula) -> SimplificationResult
{
use crate::Formula;
@ -257,6 +341,8 @@ pub(crate) fn simplify(formula: &mut crate::Formula) -> Result<(), crate::Error>
if remove_unnecessary_exists_parameters(formula)? == SimplificationResult::Simplified
|| simplify_quantified_formulas_without_parameters(formula)
== SimplificationResult::Simplified
|| join_nested_quantified_formulas_of_same_type(formula)
== SimplificationResult::Simplified
|| simplify_trivial_n_ary_formulas(formula) == SimplificationResult::Simplified
{
continue;