diff --git a/src/ir/Module.h b/src/ir/Module.h
new file mode 100644
index 000000000..d61a42add
--- /dev/null
+++ b/src/ir/Module.h
@@ -0,0 +1,24 @@
+/*
+ * Module.h
+ *
+ *  Created on: 04.01.2013
+ *      Author: chris
+ */
+
+#ifndef MODULE_H_
+#define MODULE_H_
+
+namespace storm {
+
+namespace ir {
+
+class Module {
+
+};
+
+}
+
+}
+
+
+#endif /* MODULE_H_ */
diff --git a/src/ir/Program.h b/src/ir/Program.h
new file mode 100644
index 000000000..70797f40f
--- /dev/null
+++ b/src/ir/Program.h
@@ -0,0 +1,35 @@
+/*
+ * Program.h
+ *
+ *  Created on: 04.01.2013
+ *      Author: chris
+ */
+
+#ifndef PROGRAM_H_
+#define PROGRAM_H_
+
+#include "src/ir/expressions/ConstantExpression.h"
+#include "Module.h"
+#include "RewardModel.h"
+
+namespace storm {
+
+namespace ir {
+
+class Program {
+public:
+	enum ModelType {DTMC, CTMC, MDP, CTMDP} modelType;
+	std::map<std::string, storm::ir::expressions::ConstantExpression> undefinedConstantExpressions;
+	std::vector<storm::ir::Module> modules;
+	std::map<std::string, storm::ir::RewardModel> rewards;
+
+	std::string toString() {
+		return std::string("prog!");
+	}
+};
+
+}
+
+}
+
+#endif /* PROGRAM_H_ */
diff --git a/src/ir/RewardModel.h b/src/ir/RewardModel.h
new file mode 100644
index 000000000..b53194668
--- /dev/null
+++ b/src/ir/RewardModel.h
@@ -0,0 +1,24 @@
+/*
+ * RewardModel.h
+ *
+ *  Created on: 04.01.2013
+ *      Author: chris
+ */
+
+#ifndef REWARDMODEL_H_
+#define REWARDMODEL_H_
+
+namespace storm {
+
+namespace ir {
+
+class RewardModel {
+
+};
+
+}
+
+}
+
+
+#endif /* REWARDMODEL_H_ */
diff --git a/src/ir/expressions/BooleanConstantExpression.h b/src/ir/expressions/BooleanConstantExpression.h
new file mode 100644
index 000000000..5d36598b2
--- /dev/null
+++ b/src/ir/expressions/BooleanConstantExpression.h
@@ -0,0 +1,66 @@
+/*
+ * BooleanConstantExpression.h
+ *
+ *  Created on: 04.01.2013
+ *      Author: chris
+ */
+
+#ifndef BOOLEANCONSTANTEXPRESSION_H_
+#define BOOLEANCONSTANTEXPRESSION_H_
+
+#include "ConstantExpression.h"
+
+namespace storm {
+
+namespace ir {
+
+namespace expressions {
+
+class BooleanConstantExpression : public ConstantExpression {
+public:
+	BooleanConstantExpression(std::string constantName) : ConstantExpression(constantName) {
+		defined = false;
+		value = false;
+	}
+
+	virtual ~BooleanConstantExpression() {
+
+	}
+
+	virtual std::string toString() const {
+		std::string result = this->constantName;
+		if (defined) {
+			result += "[" + boost::lexical_cast<std::string>(value) + "]";
+		}
+		return result;
+	}
+
+	bool isDefined() {
+		return defined;
+	}
+
+	bool getValue() {
+		return value;
+	}
+
+	void define(bool value) {
+		defined = true;
+		this->value = value;
+	}
+
+	bool value;
+	bool defined;
+};
+
+}
+
+}
+
+}
+
+BOOST_FUSION_ADAPT_STRUCT(
+    storm::ir::expressions::BooleanConstantExpression,
+    (std::string, constantName)
+)
+
+#endif /* BOOLEANCONSTANTEXPRESSION_H_ */
diff --git a/src/ir/expressions/DoubleConstantExpression.h b/src/ir/expressions/DoubleConstantExpression.h
new file mode 100644
index 000000000..6969965ae
--- /dev/null
+++ b/src/ir/expressions/DoubleConstantExpression.h
@@ -0,0 +1,66 @@
+/*
+ * DoubleConstantExpression.h
+ *
+ *  Created on: 04.01.2013
+ *      Author: chris
+ */
+
+#ifndef DOUBLECONSTANTEXPRESSION_H_
+#define DOUBLECONSTANTEXPRESSION_H_
+
+#include "ConstantExpression.h"
+
+namespace storm {
+
+namespace ir {
+
+namespace expressions {
+
+class DoubleConstantExpression : public ConstantExpression {
+public:
+	DoubleConstantExpression(std::string constantName) : ConstantExpression(constantName) {
+		defined = false;
+		value = 0.0;
+	}
+
+	virtual ~DoubleConstantExpression() {
+
+	}
+
+	virtual std::string toString() const {
+		std::string result = this->constantName;
+		if (defined) {
+			result += "[" + boost::lexical_cast<std::string>(value) + "]";
+		}
+		return result;
+	}
+
+	bool isDefined() {
+		return defined;
+	}
+
+	double getValue() {
+		return value;
+	}
+
+	void define(double value) {
+		defined = true;
+		this->value = value;
+	}
+
+	double value;
+	bool defined;
+};
+
+}
+
+}
+
+}
+
+BOOST_FUSION_ADAPT_STRUCT(
+    storm::ir::expressions::DoubleConstantExpression,
+    (std::string, constantName)
+)
+
+#endif /* DOUBLECONSTANTEXPRESSION_H_ */
diff --git a/src/ir/expressions/Expressions.h b/src/ir/expressions/Expressions.h
index 868fff365..5a69dc34c 100644
--- a/src/ir/expressions/Expressions.h
+++ b/src/ir/expressions/Expressions.h
@@ -17,5 +17,8 @@
 #include "UnaryBooleanFunctionExpression.h"
 #include "UnaryNumericalFunctionExpression.h"
 #include "VariableExpression.h"
+#include "BooleanConstantExpression.h"
+#include "IntegerConstantExpression.h"
+#include "DoubleConstantExpression.h"
 
 #endif /* EXPRESSIONS_H_ */
diff --git a/src/ir/expressions/IntegerConstantExpression.h b/src/ir/expressions/IntegerConstantExpression.h
new file mode 100644
index 000000000..d0df521af
--- /dev/null
+++ b/src/ir/expressions/IntegerConstantExpression.h
@@ -0,0 +1,66 @@
+/*
+ * IntegerConstantExpression.h
+ *
+ *  Created on: 04.01.2013
+ *      Author: chris
+ */
+
+#ifndef INTEGERCONSTANTEXPRESSION_H_
+#define INTEGERCONSTANTEXPRESSION_H_
+
+#include "ConstantExpression.h"
+
+namespace storm {
+
+namespace ir {
+
+namespace expressions {
+
+class IntegerConstantExpression : public ConstantExpression {
+public:
+	IntegerConstantExpression(std::string constantName) : ConstantExpression(constantName) {
+		defined = false;
+		value = 0;
+	}
+
+	virtual ~IntegerConstantExpression() {
+
+	}
+
+	virtual std::string toString() const {
+		std::string result = this->constantName;
+		if (defined) {
+			result += "[" + boost::lexical_cast<std::string>(value) + "]";
+		}
+		return result;
+	}
+
+	bool isDefined() {
+		return defined;
+	}
+
+	int getValue() {
+		return value;
+	}
+
+	void define(int value) {
+		defined = true;
+		this->value = value;
+	}
+
+	int value;
+	bool defined;
+};
+
+}
+
+}
+
+}
+
+BOOST_FUSION_ADAPT_STRUCT(
+    storm::ir::expressions::IntegerConstantExpression,
+    (std::string, constantName)
+)
+
+#endif /* INTEGERCONSTANTEXPRESSION_H_ */
diff --git a/src/parser/PrismParser.h b/src/parser/PrismParser.h
index a8073bb95..61bf5b63f 100644
--- a/src/parser/PrismParser.h
+++ b/src/parser/PrismParser.h
@@ -9,13 +9,12 @@
 #define PRISMPARSER_H_
 
 #include <boost/spirit/include/qi.hpp>
-#include <boost/spirit/include/phoenix_core.hpp>
-#include <boost/spirit/include/phoenix_operator.hpp>
-#include <boost/spirit/include/phoenix_object.hpp>
+#include <boost/spirit/include/phoenix.hpp>
 #include <boost/fusion/include/adapt_struct.hpp>
 #include <boost/fusion/include/io.hpp>
 
 #include "src/ir/expressions/Expressions.h"
+#include "src/ir/Program.h"
 
 namespace storm {
 
@@ -29,85 +28,211 @@ class PrismParser {
 
 public:
 	void test() {
-		std::string str = "const int ab = 10;";
-		std::string::const_iterator iter = str.begin();
-		std::string::const_iterator end = str.end();
-		prismGrammar<std::string::const_iterator> grammar;
+		std::string testInput = "";
+		// storm::ir::Program* result = getProgram(testInput);
+		getProgram(testInput);
+
+/*		std::cout << "Resulting program:" << std::endl;
+		std::cout << "-------------------------\n";
+		std::cout << result->toString() << std::endl;
+		std::cout << "-------------------------\n"; */
+	}
 
-		storm::ir::expressions::BaseExpression* result;
-		bool r = phrase_parse(iter, end, grammar, ascii::space, result);
+	void getProgram(std::string inputString) {
+		using qi::_val;
+		using qi::int_;
+		using qi::_r1;
+		using qi::_1;
+		using phoenix::ref;
+		using phoenix::val;
 
-		std::cout << r << std::endl;
+		prismGrammar<std::string::const_iterator> grammar;
+		std::string::const_iterator it = inputString.begin();
+		std::string::const_iterator end = inputString.end();
+		storm::ir::Program result;
 
-		if (r && iter == end) {
-			std::cout << "-------------------------\n";
-			std::cout << "Parsing succeeded\n";
-			std::cout << "result = " << result << std::endl;
-			std::cout << "-------------------------\n";
+		int resultInt = 0;
+		std::string input = "asdf";
+		bool r = phrase_parse(it, end, grammar(phoenix::val(input)), ascii::space, resultInt);
+
+		if (r && it == end) {
+			std::cout << "Parsing successful!" << std::endl;
 		} else {
-			std::string rest(iter, end);
+			std::string rest(it, end);
 			std::cout << "-------------------------\n";
 			std::cout << "Parsing failed\n";
-			std::cout << "stopped at: " << rest << "\"\n";
+			std::cout << "stopped at: \"" << rest << "\"\n";
 			std::cout << "-------------------------\n";
 		}
 	}
 
 private:
-	struct keywords_ : qi::symbols<char, unsigned> {
-		keywords_() {
-			add
-				("dtmc", 1)
-				("ctmc", 2)
-				("mdp", 3)
-				("ctmdp", 4)
-				("const", 5)
-				("int", 6)
-				("bool", 7)
-				("module", 8)
-				("endmodule", 9)
-				("rewards", 10)
-				("endrewards", 11)
-				("true", 12)
-				("false", 13)
-			;
-		}
-	};
-
-	struct variables_ : qi::symbols<char, std::string> {
-		// Intentionally left empty. This map is filled during parsing.
-	};
-
-	struct modules_ : qi::symbols<char, unsigned> {
-		// Intentionally left empty. This map is filled during parsing.
-	};
-
 	template<typename Iterator>
-	struct prismGrammar : qi::grammar<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> {
+	struct prismGrammar : qi::grammar<Iterator, int(std::string), ascii::space_type> {
 
 		prismGrammar() : prismGrammar::base_type(start) {
-			// identifierName %= qi::lexeme[qi::char_("a-zA-Z_") >> *qi::char_("a-zA-Z_0-9")];
-			// integerConstantDefinition %= qi::lit("const") >> qi::lit("int") >> identifierName >> "=" >> qi::int_ >> ";";
-
-			start %= literalExpression;
+			using qi::_val;
+			using qi::int_;
+			using qi::_r1;
+			using qi::_1;
+			using phoenix::ref;
+
+			// start = constantDefinitionList(phoenix::ref(qi::_r1), phoenix::ref(qi::_r1));
+			start = qi::lit(qi::_r1) >> int_;
+			constantDefinitionList = qi::int_;
+
+			variableDefinition %= (booleanVariableDefinition | integerVariableDefinition);
+			booleanVariableDefinition = (freeIdentifierName >> qi::lit(":") >> qi::lit("bool") >> qi::lit(";"))[phoenix::bind(booleanVariables_.add, qi::_1, phoenix::new_<storm::ir::expressions::VariableExpression>(qi::_1)), phoenix::bind(allVariables_.add, qi::_1, phoenix::new_<storm::ir::expressions::VariableExpression>(qi::_1)), qi::_val = phoenix::new_<storm::ir::expressions::VariableExpression>(qi::_1)];
+			integerVariableDefinition = (freeIdentifierName >> qi::lit(":") >> qi::lit("[") >> integerConstantExpression >> qi::lit("..") >> integerConstantExpression >> qi::lit("]") >> qi::lit(";"))[phoenix::bind(integerVariables_.add, qi::_1, phoenix::new_<storm::ir::expressions::VariableExpression>(qi::_1)), phoenix::bind(allVariables_.add, qi::_1, phoenix::new_<storm::ir::expressions::VariableExpression>(qi::_1)), qi::_val = phoenix::new_<storm::ir::expressions::VariableExpression>(qi::_1)];
+
+			constantDefinition %= (definedConstantDefinition | undefinedConstantDefinition);
+			definedConstantDefinition %= (definedBooleanConstantDefinition | definedIntegerConstantDefinition | definedDoubleConstantDefinition);
+			undefinedConstantDefinition %= (undefinedBooleanConstantDefinition | undefinedIntegerConstantDefinition | undefinedDoubleConstantDefinition);
+			definedBooleanConstantDefinition = (qi::lit("const") >> qi::lit("bool") >> freeIdentifierName >> qi::lit("=") >> booleanLiteralExpression >> qi::lit(";"))[phoenix::bind(booleanConstants_.add, qi::_1, qi::_2), phoenix::bind(allConstants_.add, qi::_1, qi::_2), qi::_val = qi::_2];
+			definedIntegerConstantDefinition = (qi::lit("const") >> qi::lit("int") >> freeIdentifierName >> qi::lit("=") >> integerLiteralExpression >> qi::lit(";"))[phoenix::bind(integerConstants_.add, qi::_1, qi::_2), phoenix::bind(allConstants_.add, qi::_1, qi::_2), qi::_val = qi::_2];
+			definedDoubleConstantDefinition = (qi::lit("const") >> qi::lit("double") >> freeIdentifierName >> qi::lit("=") >> doubleLiteralExpression >> qi::lit(";"))[phoenix::bind(doubleConstants_.add, qi::_1, qi::_2), phoenix::bind(allConstants_.add, qi::_1, qi::_2), qi::_val = qi::_2];
+			undefinedBooleanConstantDefinition = (qi::lit("const") >> qi::lit("bool") >> freeIdentifierName >> qi::lit(";"))[phoenix::bind(booleanConstants_.add, qi::_1, phoenix::new_<storm::ir::expressions::BooleanConstantExpression>(qi::_1)), phoenix::bind(allConstants_.add, qi::_1, phoenix::new_<storm::ir::expressions::BooleanConstantExpression>(qi::_1)), qi::_val = phoenix::new_<storm::ir::expressions::BooleanConstantExpression>(qi::_1)];
+			undefinedIntegerConstantDefinition = (qi::lit("const") >> qi::lit("int") >> freeIdentifierName >> qi::lit(";"))[phoenix::bind(integerConstants_.add, qi::_1, phoenix::new_<storm::ir::expressions::IntegerConstantExpression>(qi::_1)), phoenix::bind(allConstants_.add, qi::_1, phoenix::new_<storm::ir::expressions::IntegerConstantExpression>(qi::_1)), qi::_val = phoenix::new_<storm::ir::expressions::IntegerConstantExpression>(qi::_1)];
+			undefinedDoubleConstantDefinition = (qi::lit("const") >> qi::lit("double") >> freeIdentifierName >> qi::lit(";"))[phoenix::bind(doubleConstants_.add, qi::_1, phoenix::new_<storm::ir::expressions::DoubleConstantExpression>(qi::_1)), phoenix::bind(allConstants_.add, qi::_1, phoenix::new_<storm::ir::expressions::DoubleConstantExpression>(qi::_1)), qi::_val = phoenix::new_<storm::ir::expressions::DoubleConstantExpression>(qi::_1)];
+
+			expression %= (booleanExpression | integerExpression | doubleExpression);
+
+			booleanExpression %= orExpression;
+			orExpression = andExpression[qi::_val = qi::_1] >> *(qi::lit("|") >> andExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryBooleanFunctionExpression>(qi::_val, qi::_1, storm::ir::expressions::BinaryBooleanFunctionExpression::OR)];
+			andExpression = atomicBooleanExpression[qi::_val = qi::_1] >> *(qi::lit("&") >> atomicBooleanExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryBooleanFunctionExpression>(qi::_val, qi::_1, storm::ir::expressions::BinaryBooleanFunctionExpression::AND)];
+			atomicBooleanExpression %= (relativeExpression | booleanVariableExpression | qi::lit("(") >> booleanExpression >> qi::lit(")") | booleanLiteralExpression | booleanConstantExpression);
+			relativeExpression = (integerExpression >> relations_ >> integerExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryRelationExpression>(qi::_1, qi::_3, qi::_2)];
+
+			integerExpression %= integerPlusExpression;
+			integerPlusExpression = integerMultExpression[qi::_val = qi::_1] >> *(qi::lit("+") >> integerMultExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryNumericalFunctionExpression>(qi::_val, qi::_1, storm::ir::expressions::BinaryNumericalFunctionExpression::PLUS)];
+			integerMultExpression %= atomicIntegerExpression[qi::_val = qi::_1] >> *(qi::lit("*") >> atomicIntegerExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryNumericalFunctionExpression>(qi::_val, qi::_1, storm::ir::expressions::BinaryNumericalFunctionExpression::TIMES)];
+			atomicIntegerExpression %= (integerVariableExpression | qi::lit("(") >> integerExpression >> qi::lit(")") | integerConstantExpression);
+
+			doubleExpression %= doublePlusExpression;
+			doublePlusExpression = doubleMultExpression[qi::_val = qi::_1] >> *(qi::lit("+") >> doubleMultExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryNumericalFunctionExpression>(qi::_val, qi::_1, storm::ir::expressions::BinaryNumericalFunctionExpression::PLUS)];
+			doubleMultExpression %= atomicDoubleExpression[qi::_val = qi::_1] >> *(qi::lit("*") >> atomicDoubleExpression)[qi::_val = phoenix::new_<storm::ir::expressions::BinaryNumericalFunctionExpression>(qi::_val, qi::_1, storm::ir::expressions::BinaryNumericalFunctionExpression::TIMES)];
+			atomicDoubleExpression %= (qi::lit("(") >> doubleExpression >> qi::lit(")") | doubleConstantExpression);
 
 			literalExpression %= (booleanLiteralExpression | integerLiteralExpression | doubleLiteralExpression);
 			booleanLiteralExpression = qi::bool_[qi::_val = phoenix::new_<storm::ir::expressions::BooleanLiteral>(qi::_1)];
 			integerLiteralExpression = qi::int_[qi::_val = phoenix::new_<storm::ir::expressions::IntegerLiteral>(qi::_1)];
 			doubleLiteralExpression = qi::double_[qi::_val = phoenix::new_<storm::ir::expressions::DoubleLiteral>(qi::_1)];
-		}
 
-		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> start;
+			constantExpression %= (booleanConstantExpression | integerConstantExpression | doubleConstantExpression);
+			booleanConstantExpression %= (booleanConstants_ | booleanLiteralExpression);
+			integerConstantExpression %= (integerConstants_ | integerLiteralExpression);
+			doubleConstantExpression %= (doubleConstants_ | doubleLiteralExpression);
 
-		// The expression rules.
+			variableExpression = (integerVariableExpression | booleanVariableExpression);
+			integerVariableExpression = integerVariables_;
+			booleanVariableExpression = booleanVariables_;
+
+			freeIdentifierName %= qi::lexeme[(qi::alpha >> *(qi::alnum)) - allVariables_ - allConstants_];
+		}
+
+		// The starting point of the grammar.
+		qi::rule<Iterator, int(std::string), ascii::space_type> start;
+
+		qi::rule<Iterator, int(), ascii::space_type> constantDefinitionList;
+
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> variableDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> booleanVariableDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerVariableDefinition;
+
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> constantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> undefinedConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> definedConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> undefinedBooleanConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> undefinedIntegerConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> undefinedDoubleConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> definedBooleanConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> definedIntegerConstantDefinition;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> definedDoubleConstantDefinition;
+
+		qi::rule<Iterator, std::string(), ascii::space_type> freeIdentifierName;
+
+		// The starting point for arbitrary expressions.
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> expression;
+
+		// Rules with boolean result type.
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> booleanExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> orExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> andExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> atomicBooleanExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> relativeExpression;
+
+		// Rules with integer result type.
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerPlusExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerMultExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> atomicIntegerExpression;
+
+		// Rules with double result type.
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> doubleExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> doublePlusExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> doubleMultExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> atomicDoubleExpression;
+
+		// Rules for variable recognition.
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> variableExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> booleanVariableExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerVariableExpression;
+
+		// Rules for constant recognition.
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> constantExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> booleanConstantExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerConstantExpression;
+		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> doubleConstantExpression;
+
+		// Rules for literal recognition.
 		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> literalExpression;
 		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> booleanLiteralExpression;
 		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> integerLiteralExpression;
 		qi::rule<Iterator, storm::ir::expressions::BaseExpression*(), ascii::space_type> doubleLiteralExpression;
 
-		// qi::rule<Iterator, intConstDef(), ascii::space_type> integerConstantDefinition;
-		// qi::rule<Iterator, std::string(), ascii::space_type> identifierName;
-
+		struct keywordsStruct : qi::symbols<char, unsigned> {
+			keywordsStruct() {
+				add
+					("dtmc", 1)
+					("ctmc", 2)
+					("mdp", 3)
+					("ctmdp", 4)
+					("const", 5)
+					("int", 6)
+					("bool", 7)
+					("module", 8)
+					("endmodule", 9)
+					("rewards", 10)
+					("endrewards", 11)
+					("true", 12)
+					("false", 13)
+				;
+			}
+		} keywords_;
+
+		struct relationalOperatorStruct : qi::symbols<char, storm::ir::expressions::BinaryRelationExpression::RelationType> {
+			relationalOperatorStruct() {
+				add
+					("==", storm::ir::expressions::BinaryRelationExpression::EQUAL)
+					("<", storm::ir::expressions::BinaryRelationExpression::LESS)
+					("<=", storm::ir::expressions::BinaryRelationExpression::LESS_OR_EQUAL)
+					(">", storm::ir::expressions::BinaryRelationExpression::GREATER)
+					(">=", storm::ir::expressions::BinaryRelationExpression::GREATER_OR_EQUAL)
+				;
+			}
+		} relations_;
+
+		struct variablesStruct : qi::symbols<char, storm::ir::expressions::BaseExpression*> {
+			// Intentionally left empty. This map is filled during parsing.
+		} integerVariables_, booleanVariables_, allVariables_ ;
+
+		struct constantsStruct : qi::symbols<char, storm::ir::expressions::BaseExpression*> {
+			// Intentionally left empty. This map is filled during parsing.
+		} integerConstants_, booleanConstants_, doubleConstants_, allConstants_;
+
+		struct modulesStruct : qi::symbols<char, unsigned> {
+			// Intentionally left empty. This map is filled during parsing.
+		} modules_;
 	};
 };