Mathematician:Levi ben Gershon

Mathematician
French Jewish philosopher, Talmudist, mathematician, physician and astronomer/astrologer.

Notable for publishing an early proof using the principle of mathematical induction.

Anticipated 's error theory.

One of the first astronomers to estimate the distance of the fixed stars to a reasonable degree of accuracy (of the order of $100$ light years).

Refuted 's model of astronomy by direct observation, paving the way for the new model of more than $2$ centuries later.

Was involved in a lively debate about Euclid's $5$th postulate, and whether it could be derived from the other $4$.

Nationality
French

History

 * Born: 1288 in Bagnols now Bagnols sur Cèze, Provence, France
 * Died: 20 April 1344 in Avignon, France

Theorems and Definitions

 * Inventor of Jacob's Staff

Publications

 * 1317 -- 1329: Sefer Milhamot Ha-Shem ("The Wars of the Lord")


 * 1321: Maaseh Hoshev ("Work of Calculation", "Art of Calculation" or "Art of the Computer", or, by means of a Hebrew pun: "Clever Work") on mathematics
 * (often confused with Sefer Hamispar ("The Book of Number"), by )


 * 1342: A portion of Sefer Milhamot Ha-Shem containing a survey of astronomy translated into Latin


 * 1342: De sinibus, chordiis et arcubus ("On Sines, Chords and Arcs"), on trigonometry
 * 1343: ("The Harmony of Numbers") (contains a proof of Consecutive Integers which are Powers of 2 or 3)


 * Two geometry books:
 * A commentary and introduction to the first five books of Euclid, but not presented axiomatically
 * Science of Geometry of which only a fragment has survived


 * A number of non-mathematical works

Also known as
Some sources give his name as Levi ben Gerson, and others as Levi ben Gershom.

Better known by:
 * the Greek form of his name: Gersonides
 * his Latinized name (Magister) Leo Hebraeus
 * in Hebrew as RaLBaG (by the abbreviation of first letters of Rabbi Levi Ben Gershon with vowels added for ease of pronunciation)

Less commonly he can be seen referred to as Gersoni, Leo de Bagnols, Leo de Balneolis or Leo Judaeus.

It could be complicated identifying someone specifically before the invention of surnames.