Dénes Kőnig (Budapest, 1884 – 1944) A mathematician of Jewish origin, he wrote the first textbook on graph theory. He wanted to turn graph theory into a respectable mathematical discipline. In 1907, he received a doctorate in Budapest for his thesis on the rotation of finite groups in a multidimensional space. In 1941, he helped many persecuted Jewish mathematicians, but in 1944, during the Nazi occupation of Hungary and the subsequent persecution of all Hungarian Jews, he sadly committed suicide.