Paul Walker, Deputy Director for Academic Programs, Center for Middle Eastern Studies, University of Chicago, (Ph.D. University of Chicago, 1974). A former director of the American Research Center in Cairo (1976-86), he has published more than a dozen books, among them Early Philosophical Shiism: The Ismaili Neoplatonism of Abū Yaʿqūb al-Sijistānī (Cambridge, 1993); Ḥamīd al-Dīn al-Kirmānī: Ismaili Thought in the Age of al-Ḥākim (London, 1999); Caliph of Cairo: al-Hakim bi-Amr Allah, 996-1021 (Cairo, 2009).