HAI (939-1038)  , Jewish Talmudical scholar, was born in 939 . He was educated by his father Sherira, gaon of Pombeditha (Pumbedita), whom he afterwards assisted in his work . They were cast into prison for a short time by the caliph Qadir, and subsequently on Sherira's death Hai was appointed gaon in his place (998) . This office he held till his death on the 28th of March 1038 . He is famous chiefly for his answers to problems of ritual and civil law . He composed important treatises on Talmudic law and the Mishnah; many poems are also attributed to him on doubtful authority . In his responsa he laid stress on custom and tradition provided no infringement of the law were involved, and was essentially conservative in theology . He had considerable knowledge not only of religious movements within the Jewish body, but also of Mahommedan theology and controversial method, and frequently consulted theologians of other beliefs . See Steinschneider, Hebr . Ubersetz. p . 910, and article in Jewish Encyclopedia, vi . 153 .