Mathematics in the service of the Jewish calendar as manifest in ‘Yesod Olam’- Ilana Wartenberg

In the Jewish year 5070 Isaac Israeli ben Joseph the Younger composed an extensive and highly scientific treatise on the Jewish calendar. The first of the five books of Yesod Olam is dedicated mainly to Euclidean geometry and spherical trigonometry. Presented here is a discussion of the mathematical materials and their direct or indirect relevance to the Jewish calendar and in particular, the non-traditional partial transmission of Euclid’s Elements.