 Avempace wrote a letter to Abu Zayd ‛Abd ar-Rahman Ibn Sayyid al-Muhandis (IB-coll-alawi: 84–87) about a preliminary question from the first book of the Conic Sections of Apollonius of Perga (ca. 200 BC). In another letter to his disciple ‛Ali Ibn al-Imam (IB-coll-alawi: 88–96) Avempace mentions Ibn Sayyid as the discoverer of new procedures in geometry. In addition to this letter, one passage in his Commentary on the  Physics[16]  and another in the Book of animals (IB-BA: 74) deal with the Conic Sections in a sketchy way. Ahmed Djebbar studied Ibn Sayyid and Avempace and gathered that both Andalusians were innovative in their study of warped surfaces resulting from the intersection of conic and non-conic  surfaces[17].