diff --git a/lib/mealy.hpp b/lib/mealy.hpp
index 9f6d51f..5f61617 100644
--- a/lib/mealy.hpp
+++ b/lib/mealy.hpp
@@ -39,6 +39,13 @@ inline bool is_complete(const mealy & m){
 	return true;
 }
 
+inline bool defined(mealy const & m, state s, input i) {
+	if (s >= m.graph.size()) return false;
+	if (i >= m.graph[s].size()) return false;
+	if (m.graph[s][i].to == state(-1) || m.graph[s][i].output == output(-1)) return false;
+	return true;
+}
+
 inline mealy::edge apply(mealy const & m, state state, input input){
 	return m.graph[state][input];
 }
diff --git a/lib/read_mealy_from_dot.cpp b/lib/read_mealy_from_dot.cpp
index 116ba54..c94fccc 100644
--- a/lib/read_mealy_from_dot.cpp
+++ b/lib/read_mealy_from_dot.cpp
@@ -49,6 +49,9 @@ mealy read_mealy_from_dot(std::istream & in, translation & t){
 		if(t.input_indices.count(input) < 1) t.input_indices[input] = t.max_input++;
 		if(t.output_indices.count(output) < 1) t.output_indices[output] = t.max_output++;
 
+		if(defined(m, state_indices[lh], t.input_indices[input]))
+			throw runtime_error("Nondeterministic machine");
+
 		// add edge
 		m.graph.resize(max_state);
 		auto & v = m.graph[state_indices[lh]];
diff --git a/lib/read_mealy_from_txt.cpp b/lib/read_mealy_from_txt.cpp
new file mode 100644
index 0000000..6a1d75a
--- /dev/null
+++ b/lib/read_mealy_from_txt.cpp
@@ -0,0 +1,76 @@
+#include "read_mealy_from_txt.hpp"
+#include "mealy.hpp"
+
+#include <cassert>
+#include <fstream>
+#include <sstream>
+#include <string>
+
+#include <iostream>
+
+using namespace std;
+
+mealy read_mealy_from_txt(std::istream & in) {
+	mealy m;
+
+	state max_state = 0;
+	input max_input = 0;
+	output max_output = 0;
+
+	string line;
+	while (getline(in, line)) {
+		state from, to;
+		input i;
+		output o;
+		string seperator;
+
+		stringstream ss(line);
+		ss >> from >> seperator >> i >> seperator >> o >> seperator >> to;
+
+		if (from >= max_state) max_state = from + 1;
+		if (to >= max_state) max_state = to + 1;
+		if (i >= max_input) max_input = i + 1;
+		if (o >= max_output) max_output = o + 1;
+
+		if (defined(m, from, i)) throw runtime_error("Nondeterministic machine");
+
+		m.graph.resize(max_state);
+		auto & v = m.graph[from];
+		v.resize(max_input);
+		v[i] = mealy::edge(to, o);
+
+		assert(defined(m, to, i));
+	}
+
+	m.graph_size = max_state;
+	m.input_size = max_input;
+	m.output_size = max_output;
+
+	if (m.graph_size == 0) throw runtime_error("Empty state set");
+	if (m.input_size == 0) throw runtime_error("Empty input set");
+	if (m.output_size == 0) throw runtime_error("Empty output set");
+	if (!is_complete(m)) throw runtime_error("Partial machine");
+	return m;
+}
+
+mealy read_mealy_from_txt(const std::string & filename) {
+	std::ifstream file(filename);
+	return read_mealy_from_txt(file);
+}
+
+
+translation create_translation_for_mealy(const mealy & m) {
+	translation t;
+	t.max_input = m.input_size;
+	t.max_output = m.output_size;
+
+	for (input i = 0; i < t.max_input; ++i) {
+		t.input_indices[to_string(i)] = i;
+	}
+
+	for (output o = 0; o < t.max_output; ++o) {
+		t.output_indices[to_string(o)] = o;
+	}
+
+	return t;
+}
diff --git a/lib/read_mealy_from_txt.hpp b/lib/read_mealy_from_txt.hpp
new file mode 100644
index 0000000..cb8e3d0
--- /dev/null
+++ b/lib/read_mealy_from_txt.hpp
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "types.hpp"
+#include "read_mealy_from_dot.hpp"
+
+#include <iosfwd>
+
+struct mealy;
+
+/// \brief reads a mealy machine from plain txt file (as provided by A. T. Endo)
+/// States, inputs and outputs in these files are already integral (and contiguous)
+mealy read_mealy_from_txt(std::istream & in);
+mealy read_mealy_from_txt(std::string const & filename);
+
+translation create_translation_for_mealy(mealy const & m);