ابن الشاطر
Nasir al-Din al-Tusi, the creator of the Tusi Couple, also worked heavily to expose the problems present in Ptolemy's work. In 1261, Tusi published his Tadkhira, which contained 16 fundamental problems he found with Ptolemaic astronomy, and by doing this, set off a chain of Islamic scholars that would attempt to solve these problems. Scholars such as Qutb al-Din al-Shirazi, Ibn al-Shatir, and Shams al-Din al-Khafri all worked to produce new models for solving Tusi's 16 Problems, and the models they worked to create would become widely adopted by astronomers for use in their own works.