Abraham Bar Hiyya

Abraham Bar Hiyya was born in 1092 and died in 1167. He was a Jewish mathematician and astronomer who lived in Spain. It was also known by its Latin name: Savarsoda, which means governor of the city. He was educated in one of the Arab principalities of the Caliphate of Cordoba, but it was in Barcelona that Abraham wrote his original works in Hebrew.

Two of his works with mathematical contents are known:
- the first Hebrew encyclopedia on mathematics, astronomy, optics and music, called Yesodey ha-Tevuna u-Migdal ha-Emuna;
- a work of practical geometry called Hibbur ha-Meshiha we-ha-Tishboret from 1116. This work was translated into Latin in 1145 by Plato de Tivoli under the name Liber embadorum.

Although the latter was intended to assist Spanish and French Jews in calculating the measurement of fields, it contains some definitions, axioms and theorems of Euclid. Geometric justifications are also found in Islamic style to justify algebraic problems, including the equations of the 2nd degree.