Who did more ring theory, Cahit Arf or Sind ibn Ali?
Sind ibn Ali He is known to have translated and modified the Zij al-Sindhind. The Zij al-Sindhind was the first astronomical table ever introduced in the Muslim World. As a mathematician Sind ibn ʿAlī was a colleague of al-Khwarizmi and worked closely with Yaqūb ibn Tāriq together they calculated the diameter of the Earth and other astronomical bodies. He also wrote a commentary on "Kitāb al-ğabr wa-l-muqābala" and helped prove the works of al-Khwarizmi. The decimal point notation to the Arabic numerals was introduced by Sind ibn Ali.
Ali Qushji Ala al-Dīn Ali ibn Muhammed (1403 – 16 December 1474), known as Ali Qushji (Ottoman Turkish/Persian language: علی قوشچی, "kuşçu" – falconer in Turkish; Latin: "Ali Kushgii") was an astronomer, mathematician and physicist originally from Samarkand, who settled in the Ottoman Empire some time before 1472. As a disciple of Ulugh Beg, he is best known for the development of astronomical physics independent from natural philosophy, and for providing empirical evidence for the Earth's rotation in his treatise, "Concerning the Supposed Dependence of Astronomy upon Philosophy". In addition to his contributions to Ulugh Beg's famous work Zij-i-Sultani and to the founding of Sahn-ı Seman Medrese, one of the first centers for the study of various traditional Islamic sciences in the Ottoman caliphate, Ali Kuşçu was also the author of several scientific works and textbooks on astronomy.