diff --git a/CMakeLists.txt b/CMakeLists.txt
index f0f4e0e..e5e9ee7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.0)
 project(cnorxz)
 
 execute_process(COMMAND bash "-c" "git rev-parse HEAD" OUTPUT_VARIABLE GIT_HASH OUTPUT_STRIP_TRAILING_WHITESPACE)
-execute_process(COMMAND bash "-c" "git tag -l --sort=refname v* | tail -n1" OUTPUT_VARIABLE GIT_TAG OUTPUT_STRIP_TRAILING_WHITESPACE)
+execute_process(COMMAND bash "-c" "git tag -l --sort=refname 'v*' | tail -n1" OUTPUT_VARIABLE GIT_TAG OUTPUT_STRIP_TRAILING_WHITESPACE)
 execute_process(COMMAND bash "-c" "git rev-list -n 1 ${GIT_TAG}" OUTPUT_VARIABLE GIT_TAG_HASH OUTPUT_STRIP_TRAILING_WHITESPACE)
 string(SUBSTRING ${GIT_TAG} 1 -1 VERSION)
 if(NOT (${GIT_HASH} EQUAL ${GIT_TAG_HASH}))
diff --git a/src/include/ranges/mrange.cc.h b/src/include/ranges/mrange.cc.h
index 64ac367..875b06d 100644
--- a/src/include/ranges/mrange.cc.h
+++ b/src/include/ranges/mrange.cc.h
@@ -624,10 +624,10 @@ namespace CNORXZ
     template <class... Ranges>
     Vector<Uuid> MRange<Ranges...>::key() const
     {
-    	Vector<Uuid> key = iter<0,sizeof...(Ranges)>
+    	Vector<Uuid> k = iter<0,sizeof...(Ranges)>
 	    ( [&](auto i) { return std::get<i>( mRs ); },
 	      [](const auto&... e) { return Vector<Uuid> { e->id()... }; } );
-	return key;
+	return k;
     }
 
     /************************
diff --git a/src/include/ranges/range_base.cc.h b/src/include/ranges/range_base.cc.h
index 8c80a4f..23fe348 100644
--- a/src/include/ranges/range_base.cc.h
+++ b/src/include/ranges/range_base.cc.h
@@ -6,8 +6,11 @@
 #include "dindex.h"
 #include "mrange.h"
 
+//#include "crange.h"
+
 namespace CNORXZ
 {
+
     template <class Range>
     decltype(auto) RangeInterface<Range>::begin() const
     {
diff --git a/src/include/ranges/range_base.h b/src/include/ranges/range_base.h
index 4d986dc..1b91c86 100644
--- a/src/include/ranges/range_base.h
+++ b/src/include/ranges/range_base.h
@@ -68,6 +68,8 @@ namespace CNORXZ
 	DIndex end() const;
 	RangePtr orig() const;
 	
+	//virtual Vector<Uuid> key2() const { return Vector<Uuid>(); }
+
 	friend RangeFactoryBase;
 	
     protected:
@@ -75,8 +77,8 @@ namespace CNORXZ
 	RangeBase();
 	RangeBase(const RangePtr& rel);
 
-	virtual Vector<Uuid> key() const = 0;
 	
+	virtual Vector<Uuid> key() const = 0;
 	// delete copy/move???
 	Uuid mId = {0,0};
 	Wptr<RangeBase> mThis;
diff --git a/src/lib/ranges/range_base.cc b/src/lib/ranges/range_base.cc
index 52091fe..b17abfe 100644
--- a/src/lib/ranges/range_base.cc
+++ b/src/lib/ranges/range_base.cc
@@ -37,6 +37,7 @@ namespace CNORXZ
     
     RangePtr RangeFactoryBase::getRegistered(const TypeInfo& info, const RangePtr& r)
     {
+	CXZ_ASSERT(r != nullptr, "got range ptr to null");
 	auto& rx = sCreated[info.hash_code()][r->key()];
 	if(rx == nullptr){
 	    rx = r;
diff --git a/src/lib/ranges/yrange.cc b/src/lib/ranges/yrange.cc
index 04d7536..9b041b8 100644
--- a/src/lib/ranges/yrange.cc
+++ b/src/lib/ranges/yrange.cc
@@ -425,14 +425,14 @@ namespace CNORXZ
     
     void YRangeFactory::make()
     {
-	Vector<Uuid> key(mRVec.size());
-	std::transform(mRVec.begin(), mRVec.end(), key.begin(),
+	Vector<Uuid> k(mRVec.size());
+	std::transform(mRVec.begin(), mRVec.end(), k.begin(),
 		       [&](const RangePtr& r) { return r->id(); } );
-	mProd = this->fromCreated(typeid(YRange), key);
+	mProd = this->fromCreated(typeid(YRange), k);
 	if(mProd == nullptr){
 	    mProd = std::shared_ptr<YRange>
 		( new YRange( std::move(mRVec) ) );
-	    this->addToCreated(typeid(YRange), key, mProd);
+	    this->addToCreated(typeid(YRange), k, mProd);
 	}
     }
 
@@ -507,10 +507,10 @@ namespace CNORXZ
     
     Vector<Uuid> YRange::key() const
     {
-	Vector<Uuid> key(mRVec.size());
-	std::transform(mRVec.begin(), mRVec.end(), key.begin(),
+	Vector<Uuid> k(mRVec.size());
+	std::transform(mRVec.begin(), mRVec.end(), k.begin(),
 		       [&](const RangePtr& r) { return r->id(); } );
-	return key;
+	return k;
     }
 
     YRange::YRange(const Vector<RangePtr>& rvec) : mRVec(rvec) {}
diff --git a/src/opt/cereal/include/cer_array.cc.h b/src/opt/cereal/include/cer_array.cc.h
index 35299d5..bbbd01d 100644
--- a/src/opt/cereal/include/cer_array.cc.h
+++ b/src/opt/cereal/include/cer_array.cc.h
@@ -20,7 +20,8 @@ namespace CNORXZ
     template <class Archive>
     void MArray<T>::load(Archive& ar)
     {
-	ar(cereal::make_nvp("range", AB::mRange));
+	save_load("range", AB::mRange);
+	//ar(cereal::make_nvp("range", AB::mRange));
 	ar(cereal::make_nvp("data", mCont));
     }
 }
diff --git a/src/opt/cereal/include/cer_ranges.cc.h b/src/opt/cereal/include/cer_ranges.cc.h
index d0ce264..b0bda43 100644
--- a/src/opt/cereal/include/cer_ranges.cc.h
+++ b/src/opt/cereal/include/cer_ranges.cc.h
@@ -85,6 +85,10 @@ namespace CNORXZ
 	ar(cereal::make_nvp("this", RB::mThis));
 	ar(cereal::make_nvp("sub", mRVec));
 	CXZ_ASSERT(RangePtr(RB::mThis).get() == this, "got corrupted range data");
+	// register range:
+	for(auto& r: mRVec){
+	    r = RangeFactoryBase::getRegistered(r->type(), r);
+	}
     }
 }
 
diff --git a/src/opt/cereal/include/range_save_load.cc.h b/src/opt/cereal/include/range_save_load.cc.h
index acde3c5..db6917c 100644
--- a/src/opt/cereal/include/range_save_load.cc.h
+++ b/src/opt/cereal/include/range_save_load.cc.h
@@ -4,15 +4,16 @@
 
 #include "ranges/range_base.h"
 #include "range_save_load.h"
+#include <cereal/cereal.hpp>
 
 namespace CNORXZ
 {
     namespace cer
     {
 	template <class Archive>
-	RangePtr save_load(Archive& ar, RangePtr& r)
+	RangePtr save_load(Archive& ar, const String& name, RangePtr& r)
 	{
-	    ar(r);
+	    ar(cereal::make_nvp(name, r));
 	    return r = RangeFactoryBase::getRegistered(r->type(), r);
 	}
     }
diff --git a/src/opt/cereal/include/range_save_load.h b/src/opt/cereal/include/range_save_load.h
index 7518379..a60f0f6 100644
--- a/src/opt/cereal/include/range_save_load.h
+++ b/src/opt/cereal/include/range_save_load.h
@@ -8,8 +8,10 @@ namespace CNORXZ
 {
     namespace cer
     {
+	// use this function to register the range in the map of the range factories
+	// (otherwise there might be more than one instance of the same range)
 	template <class Archive>
-	RangePtr save_load(Archive& ar, RangePtr& r);
+	RangePtr save_load(Archive& ar, const String& name, RangePtr& r);
     }
 }
 
diff --git a/src/opt/cereal/tests/cereal_unit_test.cc b/src/opt/cereal/tests/cereal_unit_test.cc
index 9d31ad6..edc5226 100644
--- a/src/opt/cereal/tests/cereal_unit_test.cc
+++ b/src/opt/cereal/tests/cereal_unit_test.cc
@@ -28,6 +28,43 @@ namespace
 	std::stringstream mS;
     };
 
+    class CerURange_Test : public ::testing::Test
+    {
+    protected:
+
+	CerURange_Test()
+	{
+	    mMeta = { "some", "random", "words", "with", "no", "meaning" };
+	    mR = URangeFactory(mMeta).create();
+	}
+
+	Vector<String> mMeta;
+	RangePtr mR;
+	std::stringstream mS;
+    };
+
+    class CerYRange_Test : public ::testing::Test
+    {
+    protected:
+
+	CerYRange_Test()
+	{
+	    mSize = 7;
+	    mMeta = { "some", "random", "words", "with", "no", "meaning" };
+	    mR1 = CRangeFactory(mSize).create();
+	    mR2 = URangeFactory(mMeta).create();
+	    mR = YRangeFactory({mR1,mR2}).create();
+	}
+
+	SizeT mSize;
+	Vector<String> mMeta;
+	RangePtr mR1;
+	RangePtr mR2;
+	RangePtr mR;
+	std::stringstream mS;
+	std::stringstream mS2;
+    };
+
     TEST_F(CerCRange_Test, Serialize)
     {
 	{
@@ -50,6 +87,92 @@ namespace
 	    EXPECT_TRUE(*i1 == *i2);
 	}
     }
+
+    TEST_F(CerURange_Test, Serialize)
+    {
+	{
+	    cereal::JSONOutputArchive ar(mS);
+	    ar(mR);
+	}
+	std::cout << mS.str() << std::endl;
+	RangePtr r = nullptr;
+	{
+	    cereal::JSONInputArchive ar(mS);
+	    ar(r);
+	}
+	EXPECT_EQ(r->size(), mR->size());
+	EXPECT_EQ(r->dim(), mR->dim());
+	auto i1 = r->begin();
+	auto i2 = mR->begin();
+	auto i1e = r->end();
+	auto i2e = mR->end();
+	for(; i1 != i1e; ++i1, ++i2){
+	    EXPECT_TRUE(*i1 == *i2);
+	}
+    }
+
+    TEST_F(CerYRange_Test, Serialize)
+    {
+	{
+	    cereal::JSONOutputArchive ar(mS);
+	    ar(cereal::make_nvp("mR",mR));
+	    //ar(mR);
+	}
+	std::cout << mS.str() << std::endl;
+	RangePtr r = nullptr;
+	{
+	    cereal::JSONInputArchive ar(mS);
+	    cer::save_load(ar, "mR", r);
+	}
+	EXPECT_EQ(r->size(), mR->size());
+	EXPECT_EQ(r->dim(), mR->dim());
+	auto i1 = r->begin();
+	auto i2 = mR->begin();
+	auto i1e = r->end();
+	auto i2e = mR->end();
+	for(; i1 != i1e; ++i1, ++i2){
+	    EXPECT_TRUE(*i1 == *i2);
+	}
+    }
+
+    TEST_F(CerYRange_Test, NoDuplicates)
+    {
+	{
+	    cereal::JSONOutputArchive ar(mS);
+	    ar(cereal::make_nvp("mR",mR));
+	}
+	{
+	    cereal::JSONOutputArchive ar(mS2);
+	    ar(cereal::make_nvp("mR",mR));
+	}
+	std::cout << mS.str() << std::endl;
+	RangePtr r = nullptr;
+	{
+	    cereal::JSONInputArchive ar(mS);
+	    //ar(r);
+	    cer::save_load(ar, "mR", r);
+	}
+	RangePtr r2 = nullptr;
+	{
+	    cereal::JSONInputArchive ar(mS2);
+	    //ar(r2);
+	    cer::save_load(ar, "mR", r2);
+	}
+
+	EXPECT_TRUE(r == r2);
+	EXPECT_EQ(r->size(), r2->size());
+	EXPECT_EQ(r->dim(), r2->dim());
+	for(SizeT i = 0; i != r->dim(); ++i){
+	    EXPECT_TRUE(r->sub(i) == r2->sub(i));
+	}
+	auto i1 = r->begin();
+	auto i2 = r2->begin();
+	auto i1e = r->end();
+	auto i2e = r2->end();
+	for(; i1 != i1e; ++i1, ++i2){
+	    EXPECT_TRUE(*i1 == *i2);
+	}
+    }
 }
 
 int main(int argc, char** argv)