diff --git a/lib/test_suite.cpp b/lib/test_suite.cpp
index b74521f..f33a53f 100644
--- a/lib/test_suite.cpp
+++ b/lib/test_suite.cpp
@@ -23,7 +23,7 @@ void test(const mealy & specification, const transfer_sequences & prefixes,
 					output.apply(prefix);
 					output.apply(middle);
 					output.apply(suffix);
-					output.reset();
+					if(!output.reset()) return;
 				}
 			}
 		}
@@ -51,7 +51,7 @@ void randomized_test(const mealy & specification, const transfer_sequences & pre
 		const auto & prefix = prefixes[prefix_selection(generator)];
 		current_state = apply(specification, current_state, begin(prefix), end(prefix)).to;
 
-		vector<input> middle;
+		word middle;
 		middle.reserve(min_k + 1);
 		size_t minimal_size = min_k;
 		while (minimal_size || unfair_coin(generator)) {
@@ -68,12 +68,77 @@ void randomized_test(const mealy & specification, const transfer_sequences & pre
 		output.apply(prefix);
 		output.apply(middle);
 		output.apply(suffix);
-		output.reset();
+		if(!output.reset()) return;
+	}
+}
+
+void randomized_test_suffix(const mealy & specification, const transfer_sequences & prefixes,
+                            const separating_family & separating_family, size_t min_k,
+                            size_t rnd_length, const writer & output, uint_fast32_t random_seed) {
+	vector<pair<state, word>> all_suffixes;
+	for (state s = 0; s < separating_family.size(); ++s) {
+		for (auto const & w : separating_family[s].local_suffixes) {
+			all_suffixes.emplace_back(s, w);
+		}
+	}
+
+	// state -> [(input, state)]
+	vector<vector<pair<input, state>>> reverse_machine(specification.graph_size);
+	for (state s = 0; s < specification.graph_size; ++s) {
+		for (input i = 0; i < specification.input_size; ++i) {
+			const auto t = apply(specification, s, i).to;
+			reverse_machine[t].emplace_back(i, s);
+		}
+	}
+
+	std::mt19937 generator(random_seed);
+
+	// https://en.wikipedia.org/wiki/Geometric_distribution we have the random variable Y here
+	uniform_int_distribution<> unfair_coin(0, rnd_length);
+	uniform_int_distribution<state> suffix_selection(0, all_suffixes.size() - 1);
+	uniform_int_distribution<size_t> input_selection;
+
+	while (true) {
+		const auto & state_suffix = all_suffixes[suffix_selection(generator)];
+		const auto & suffix = state_suffix.second;
+		state current_state = state_suffix.first;
+
+		word middle;
+		middle.reserve(min_k + 1);
+		size_t minimal_size = min_k;
+		while (minimal_size || unfair_coin(generator)) {
+			const auto & preds = reverse_machine[current_state];
+			if(preds.empty()) {
+				cerr << "ERROR: no predecessors for this state!\n";
+				break;
+			}
+
+			using params = decltype(input_selection)::param_type;
+			const auto & input_state
+			    = preds[input_selection(generator, params{0, preds.size() - 1})];
+
+			current_state = input_state.second;
+			middle.insert(middle.begin(), input_state.first);
+
+			if (minimal_size) minimal_size--;
+		}
+
+		const auto & prefix = prefixes[current_state];
+
+		output.apply(prefix);
+		output.apply(middle);
+		output.apply(suffix);
+		if(!output.reset()) return;
 	}
 }
 
 writer default_writer(std::vector<std::string> const & inputs) {
-	static const auto print_word = [&](word w) { for (auto && x : w) cout << inputs[x] << ' '; };
-	static const auto reset = [&] { cout << endl; };
+	static const auto print_word = [&](word w) {
+		for (auto && x : w) cout << inputs[x] << ' ';
+	};
+	static const auto reset = [&] {
+		cout << endl;
+		return bool(cout);
+	};
 	return {print_word, reset};
 }
diff --git a/lib/test_suite.hpp b/lib/test_suite.hpp
index d797b58..768d4c6 100644
--- a/lib/test_suite.hpp
+++ b/lib/test_suite.hpp
@@ -9,7 +9,7 @@
 
 struct writer {
 	std::function<void(word)> apply; // store a part of a word
-	std::function<void(void)> reset; // flush
+	std::function<bool(void)> reset; // flush, if flase is returned, testing is stopped
 };
 
 /// \brief Performs exhaustive tests with \p k_max extra states (harmonized, e.g. HSI / DS)
@@ -18,8 +18,12 @@ void test(mealy const & specification, transfer_sequences const & prefixes,
 
 /// \brief Performs random non-exhaustive tests for more states (harmonized, e.g. HSI / DS)
 void randomized_test(mealy const & specification, transfer_sequences const & prefixes,
-                                  separating_family const & separating_family, size_t min_k,
-                                  size_t rnd_length, writer const & output, uint_fast32_t random_seed);
+                     separating_family const & separating_family, size_t min_k, size_t rnd_length,
+                     writer const & output, uint_fast32_t random_seed);
+
+void randomized_test_suffix(mealy const & specification, transfer_sequences const & prefixes,
+                            separating_family const & separating_family, size_t min_k,
+                            size_t rnd_length, writer const & output, uint_fast32_t random_seed);
 
 /// \brief returns a writer which simply writes everything to cout (via inputs)
 writer default_writer(const std::vector<std::string> & inputs);
diff --git a/src/main.cpp b/src/main.cpp
index 07364fb..ba0705d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -31,6 +31,7 @@ R"(Generate a test suite
       --no-ds          Only use the classical algorithm (hsi)
       --random-ds      Choose randomly between the ds method or hsi method
       --no-suffix      Dont calculate anything smart, just do the random stuff
+      --suffix-based   Only applies in random mode. Chooses suffix first, and not prefix first
 )";
 
 using time_logger = silent_timer;
@@ -47,6 +48,7 @@ int main(int argc, char *argv[]) try {
 	const bool streaming = args.at("all").asBool() || args.at("fixed").asBool();
 	const bool random_part = args.at("all").asBool() || args.at("random").asBool();
 	const bool no_suffix = args.at("--no-suffix").asBool();
+	const bool suffix_based = args.at("--suffix-based").asBool();
 
 	const bool seed_provided = bool(args.at("--seed"));
 	const uint_fast32_t seed = seed_provided ? args.at("--seed").asLong() : 0;
@@ -153,7 +155,14 @@ int main(int argc, char *argv[]) try {
 	if(random_part){
 		time_logger t("outputting all random tests");
 		const auto k_max_ = streaming ? k_max + 1 : 0;
-		randomized_test(machine, transfer_sequences, separating_family, k_max_, rnd_length, default_writer(inputs), random_seeds[3]);
+
+		if (suffix_based) {
+			randomized_test_suffix(machine, transfer_sequences, separating_family, k_max_,
+			                       rnd_length, default_writer(inputs), random_seeds[3]);
+		} else {
+			randomized_test(machine, transfer_sequences, separating_family, k_max_, rnd_length,
+			                default_writer(inputs), random_seeds[3]);
+		}
 	}
 
 } catch (exception const & e) {
diff --git a/src/methods.cpp b/src/methods.cpp
index 03463be..be75b37 100644
--- a/src/methods.cpp
+++ b/src/methods.cpp
@@ -2,6 +2,7 @@
 #include <read_mealy.hpp>
 #include <separating_family.hpp>
 #include <splitting_tree.hpp>
+#include <test_suite.hpp>
 #include <transfer_sequences.hpp>
 #include <trie.hpp>
 
@@ -15,7 +16,7 @@
 using namespace std;
 
 static const char USAGE[] =
-R"(FSM-based test methods
+    R"(FSM-based test methods
 
     Usage:
       methods (hsi|ads) [options] <file>
@@ -25,14 +26,15 @@ R"(FSM-based test methods
       --version                Show version
       -s <seed>, --seed <seed> Specify a seed
       --non-random             Iterate inputs in specified order (as occurring in input file)
-      -k <states>              Testing extra states [default: 0]
+      -k <states>              Testing extra states [default: 1]
+      --print-suite            Prints the whole test suite
 )";
 
 int main(int argc, char * argv[]) {
 	const auto args = docopt::docopt(USAGE, {argv + 1, argv + argc}, true, __DATE__ __TIME__);
 
 	const string filename = args.at("<file>").asString();
-	const size_t k_max = args.at("-k").asLong() + 1;
+	const size_t k_max = args.at("-k").asLong();
 
 	const auto machine = [&] {
 		if (filename.find(".txt") != string::npos) {
@@ -61,54 +63,71 @@ int main(int argc, char * argv[]) {
 		if (args.at("hsi").asBool()) {
 			return create_adaptive_distinguishing_sequence(result(machine.graph_size));
 		}
-		const auto tree
-		    = create_splitting_tree(machine, args.at("--non-random").asBool() ? lee_yannakakis_style : randomized_lee_yannakakis_style, random_seeds[0]);
+		const auto tree = create_splitting_tree(machine, args.at("--non-random").asBool()
+		                                                     ? lee_yannakakis_style
+		                                                     : randomized_lee_yannakakis_style,
+		                                        random_seeds[0]);
 		return create_adaptive_distinguishing_sequence(tree);
 	});
 
 	auto pairs_fut = async([&] {
-		const auto tree
-		    = create_splitting_tree(machine, args.at("--non-random").asBool() ? min_hopcroft_style : randomized_min_hopcroft_style, random_seeds[1]);
+		const auto tree = create_splitting_tree(machine, args.at("--non-random").asBool()
+		                                                     ? min_hopcroft_style
+		                                                     : randomized_min_hopcroft_style,
+		                                        random_seeds[1]);
 		return tree.root;
 	});
 
-	auto prefixes_fut
-	    = async([&] { return create_randomized_transfer_sequences(machine, 0, random_seeds[2]); });
-
-	auto middles_fut = async([&] {
-		vector<word> all_sequences(1);
-		for (size_t k = 0; k < k_max; ++k) {
-			const auto new_sequences = all_seqs(0, machine.input_size, all_sequences);
-			all_sequences.reserve(all_sequences.size() + new_sequences.size());
-			copy(begin(new_sequences), end(new_sequences), back_inserter(all_sequences));
-		}
-		return all_sequences;
+	auto prefixes_fut = async([&] {
+		return create_transfer_sequences(args.at("--non-random").asBool()
+		                                     ? canonical_transfer_sequences
+		                                     : randomized_transfer_sequences,
+		                                 machine, 0, random_seeds[2]);
 	});
 
 	auto suffixes_fut
 	    = async([&] { return create_separating_family(sequence_fut.get(), pairs_fut.get()); });
 
-	const auto prefixes = prefixes_fut.get();
-	const auto middles = middles_fut.get();
-	const auto suffixes = suffixes_fut.get();
 	trie<input> test_suite;
+	word buffer;
 
-	const state start = 0;
-	const word empty = {};
-	for (auto && p : prefixes) {
-		const state s1 = apply(machine, start, begin(p), end(p)).to;
-		const word w1 = concat(empty, p);
-		for (auto && m : middles) {
-			const state s2 = apply(machine, s1, begin(m), end(m)).to;
-			const word w2 = concat(w1, m);
-			const auto & suffixes_for_state = suffixes[s2].local_suffixes;
-			for (auto && s : suffixes_for_state) {
-				word test = concat(w2, s);
-				test_suite.insert(test);
+	const auto suffixes = suffixes_fut.get();
+	for(state s = 0; s < suffixes.size(); ++s){
+		clog << "suffixes for " << s << endl;
+		for(auto s : suffixes[s].local_suffixes) {
+			for(auto x : s){
+				clog << x;
 			}
+			clog << endl;
 		}
 	}
 
+	const auto prefixes = prefixes_fut.get();
+	for(state s = 0; s < prefixes.size(); ++s) {
+		clog << "prefix for " << s << endl;
+		for(auto x : prefixes[s]) {
+			clog << x;
+		}
+		clog << endl;
+	}
+
+	test(machine, prefixes, suffixes, k_max,
+	     {[&buffer](auto const & w) { buffer.insert(buffer.end(), w.begin(), w.end()); },
+	      [&buffer, &test_suite]() {
+		      test_suite.insert(buffer);
+		      buffer.clear();
+			  return true;
+		  }});
+
 	const auto p = total_size(test_suite);
 	cout << p.first << '\t' << p.second << '\t' << p.first + p.second << endl;
+
+	if(args.at("--print-suite").asBool()){
+		test_suite.for_each([](const auto & w){
+			for(const auto & x : w) {
+				cout << x;
+			}
+			cout << endl;
+		});
+	}
 }