diff --git a/alib2algo/src/automaton/properties/UndistinguishableStates.cpp b/alib2algo/src/automaton/properties/UndistinguishableStates.cpp
index 125dc76b015d5ee6f2b3917abe722b744a9bb212..2e3e46156601f51e7ce3ad856eb09408dd12868a 100644
--- a/alib2algo/src/automaton/properties/UndistinguishableStates.cpp
+++ b/alib2algo/src/automaton/properties/UndistinguishableStates.cpp
@@ -10,16 +10,16 @@
 
 namespace {
 
-auto UndistinguishableStatesDFA = registration::AbstractRegister < automaton::properties::UndistinguishableStates, ext::set < ext::set < DefaultStateType > >, const automaton::DFA < > & > ( automaton::properties::UndistinguishableStates::undistinguishable, "fsm" ).setDocumentation (
+auto UndistinguishableStatesDFA = registration::AbstractRegister < automaton::properties::UndistinguishableStates, ext::set < ext::pair < DefaultStateType, DefaultStateType > >, const automaton::DFA < > & > ( automaton::properties::UndistinguishableStates::undistinguishable, "fsm" ).setDocumentation (
 "Computes the partitions of undistinguishable states states in given DFA.\n\
 \n\
 @param dfa finite automaton.\n\
-@return set of blocks of undistinguishable states" );
+@return undistinguishable states relation" );
 
-auto UndistinguishableStatesDFTA = registration::AbstractRegister < automaton::properties::UndistinguishableStates, ext::set < ext::set < DefaultStateType > >, const automaton::DFTA < > & > ( automaton::properties::UndistinguishableStates::undistinguishable, "fta" ).setDocumentation (
+auto UndistinguishableStatesDFTA = registration::AbstractRegister < automaton::properties::UndistinguishableStates, ext::set < ext::pair < DefaultStateType, DefaultStateType > >, const automaton::DFTA < > & > ( automaton::properties::UndistinguishableStates::undistinguishable, "fta" ).setDocumentation (
 "Computes the partitions of undistinguishable states states in given DFTA.\n\
 \n\
 @param dfta finite tree automaton.\n\
-@return set of blocks of undistinguishable states" );
+@return undistinguishable states relation" );
 
 } /* namespace */
diff --git a/alib2algo/src/automaton/properties/UndistinguishableStates.h b/alib2algo/src/automaton/properties/UndistinguishableStates.h
index ed6a7d682c65369656a429066675c9b05460b7ab..de9ee7ca070cbfcc80919cd26d9c32a6f5d8cd13 100644
--- a/alib2algo/src/automaton/properties/UndistinguishableStates.h
+++ b/alib2algo/src/automaton/properties/UndistinguishableStates.h
@@ -42,21 +42,6 @@ namespace properties {
  * @sa DistinguishableStates
  */
 class UndistinguishableStates {
-	template < class StateType >
-	static ext::set < ext::set < StateType > > convertUndistinguishable ( const ext::set < ext::pair < StateType, StateType > > & undistinguishable, const ext::set < StateType > & states ) {
-		ext::set < ext::set < StateType > > res;
-		for ( const StateType & state : states ) {
-			ext::set < StateType > partition;
-
-			for ( const StateType & other : states )
-				if ( undistinguishable.count ( ext::make_pair ( state, other ) ) != 0 )
-					partition.insert ( other );
-
-			res.insert ( partition );
-		}
-		return res;
-	}
-
 	template < class StateType >
 	static ext::set < ext::pair < StateType, StateType > > initial ( const ext::set < StateType > & states, const ext::set < StateType > & finals ) {
 		ext::set < ext::pair < StateType, StateType > > init;
@@ -84,7 +69,7 @@ public:
 	 * @return state partitioning of undistinguishable states
 	 */
 	template < class SymbolType, class StateType >
-	static ext::set < ext::set < StateType > > undistinguishable ( const automaton::DFA < SymbolType, StateType > & dfa );
+	static ext::set < ext::pair < StateType, StateType > > undistinguishable ( const automaton::DFA < SymbolType, StateType > & dfa );
 
 	/**
 	 * Creates state partitioning of undistinguishable states-
@@ -97,11 +82,11 @@ public:
 	 * @return state partitioning of undistinguishable states
 	 */
 	template < class SymbolType, class StateType >
-	static ext::set < ext::set < StateType > > undistinguishable ( const automaton::DFTA < SymbolType, StateType > & fta );
+	static ext::set < ext::pair < StateType, StateType > > undistinguishable ( const automaton::DFTA < SymbolType, StateType > & fta );
 };
 
 template < class SymbolType, class StateType >
-ext::set < ext::set < StateType > > UndistinguishableStates::undistinguishable ( const automaton::DFA < SymbolType, StateType > & dfa ) {
+ext::set < ext::pair < StateType, StateType > > UndistinguishableStates::undistinguishable ( const automaton::DFA < SymbolType, StateType > & dfa ) {
 	ext::set < ext::pair < StateType, StateType > > undistinguishable = initial ( dfa.getStates ( ), dfa.getFinalStates ( ) );
 
 	do {
@@ -127,11 +112,11 @@ ext::set < ext::set < StateType > > UndistinguishableStates::undistinguishable (
 
 	} while ( true );
 
-	return convertUndistinguishable ( undistinguishable, dfa.getStates ( ) );
+	return undistinguishable;
 }
 
 template < class SymbolType, class StateType >
-ext::set < ext::set < StateType > > UndistinguishableStates::undistinguishable ( const automaton::DFTA < SymbolType, StateType > & fta ) {
+ext::set < ext::pair < StateType, StateType > > UndistinguishableStates::undistinguishable ( const automaton::DFTA < SymbolType, StateType > & fta ) {
 	ext::set < ext::pair < StateType, StateType > > undistinguishable = initial ( fta.getStates ( ), fta.getFinalStates ( ) );
 
 	do {
@@ -161,7 +146,7 @@ ext::set < ext::set < StateType > > UndistinguishableStates::undistinguishable (
 
 	} while ( true );
 
-	return convertUndistinguishable ( undistinguishable, fta.getStates ( ) );
+	return undistinguishable;
 }
 
 } /* namespace properties */
diff --git a/alib2integrationtest/test-src/tests/minimizeTest.cpp b/alib2integrationtest/test-src/tests/minimizeTest.cpp
index 713ae766140b95123fd2efee8e190a9c9fc55377..836c97b43baf99aad0ee98d31302ac3474ae7b48 100644
--- a/alib2integrationtest/test-src/tests/minimizeTest.cpp
+++ b/alib2integrationtest/test-src/tests/minimizeTest.cpp
@@ -21,9 +21,10 @@ static const std::string qGenNFA ( ) {
 
 TEST_CASE ( "Minimization FA test", "[integration]" ) {
 	static const std::string qDet ( "automaton::determinize::Determinize - | automaton::simplify::Trim -" );
-	static const std::string qMinimizeHop ( qDet  + " | " + "automaton::simplify::Minimize - | automaton::simplify::Normalize -" );
-	static const std::string qMinimizeBrz ( qDet  + " | " + "automaton::simplify::MinimizeBrzozowski - | automaton::simplify::Trim - | automaton::simplify::Normalize -" );
-	static const std::string qMinimizeDis ( qDet  + " | " + "automaton::simplify::MinimizeByPartitioning - <( $gen | " + qDet + " | automaton::properties::UndistinguishableStates - ) | automaton::simplify::Normalize -" );
+	static const std::string qMinimizeHop ( qDet + " | " + "automaton::simplify::Minimize - | automaton::simplify::Normalize -" );
+	static const std::string qMinimizeBrz ( qDet + " | " + "automaton::simplify::MinimizeBrzozowski - | automaton::simplify::Trim - | automaton::simplify::Normalize -" );
+	static const std::string qMinimizeDis ( qDet + " | " + "automaton::simplify::MinimizeByPartitioning - <( $gen | " + qDet + " | automaton::properties::DistinguishableStates - | relation::RelationComplement - <( $gen | " + qDet + " | automaton::States::get - ) | relation::InducedEquivalence - ) | automaton::simplify::Normalize -" );
+	static const std::string qMinimizeUnd ( qDet + " | " + "automaton::simplify::MinimizeByPartitioning - <( $gen | " + qDet + " | automaton::properties::UndistinguishableStates - | relation::InducedEquivalence - ) | automaton::simplify::Normalize -" );
 
 
 	SECTION ( "Files tests" ) {
@@ -41,6 +42,12 @@ TEST_CASE ( "Minimization FA test", "[integration]" ) {
 				"quit compare::AutomatonCompare <( $gen | " + qMinimizeHop + " )" + " <( $gen | " + qMinimizeDis + ")"
 			};
 			TimeoutAqlTest ( 2s, qs );
+
+			qs = {
+				"execute < " + inputFile + " > $gen",
+				"quit compare::AutomatonCompare <( $gen | " + qMinimizeHop + " )" + " <( $gen | " + qMinimizeUnd + ")"
+			};
+			TimeoutAqlTest ( 2s, qs );
 		}
 	}
 
@@ -59,6 +66,12 @@ TEST_CASE ( "Minimization FA test", "[integration]" ) {
 				"quit compare::AutomatonCompare <( $gen | " + qMinimizeHop + " )" + " <( $gen | " + qMinimizeDis + ")"
 			};
 			TimeoutAqlTest ( 2s, qs );
+
+			qs = {
+				qGenNFA ( ) + " > $gen",
+				"quit compare::AutomatonCompare <( $gen | " + qMinimizeHop + " )" + " <( $gen | " + qMinimizeUnd + ")"
+			};
+			TimeoutAqlTest ( 2s, qs );
 		}
 	}
 }