From d5dd8e849f26cd5eb29ffc4ec255dd0ba53df7aa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20L=C3=BChne?= <patrick-github@luehne.de>
Date: Sat, 24 Jun 2017 16:02:48 +0200
Subject: [PATCH] =?UTF-8?q?Avoiding=20to=20decompose=20=E2=80=9Cnot?=
 =?UTF-8?q?=E2=80=9D=20expressions=20if=20they=20form=20simple=20literals.?=
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---
 .../src/pddlparse/detail/normalization/Precondition.cpp       | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp b/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp
index 765c40a..45977b4 100644
--- a/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp
+++ b/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp
@@ -120,6 +120,10 @@ normalizedAST::Literal normalizeNested(ast::ImplyPointer<ast::Precondition> &, n
 
 normalizedAST::Literal normalizeNested(ast::NotPointer<ast::Precondition> &not_, normalizedAST::DerivedPredicateDeclarations &derivedPredicates)
 {
+	// “not” expressions may be nested one time to form simple literals
+	if (not_->argument.is<ast::AtomicFormula>())
+		return std::make_unique<normalizedAST::Not<normalizedAST::AtomicFormula>>(normalize(std::move(not_->argument.get<ast::AtomicFormula>())));
+
 	std::vector<normalizedAST::VariableDeclaration *> parameters;
 	VariableStack variableStack;