945 - 1000 JUDAH HAYYUG/HAYYUJ (ibn Daub) (Spain)
Born in Fez, he was one of Menachem ben Saruk's disciples. He spent most of his life in Cordova. Although most of his writings were in Arabic, they all dealt with Hebrew grammar. He defined the Hebrew triliteral (three letter) root system, providing the foundation of the scientific study of Hebrew grammar.