Two qualifiers the source this claim rests on keeps, and this page drops. Rosen, who edited the Arabic text of this treatise and translated it in 1831, records in his preface exactly where the priority claim comes from. On p. vii he reports that Haji Khalfa states, in two passages, that Mohammed ben Musa was "the first Mussulman who had ever written on the solution of problems by the rules of completion and reduction", and quotes a marginal note in the Oxford manuscript: "This is the first book written on (the art of calculating by) completion and reduction by a Mohammedan." On p. viii he then adds: "From the manner in which our author, in his preface, speaks of the task he had undertaken, we cannot infer that he claimed to be the inventor. He says that the Caliph Al Mamun encouraged him to write a popular work on Algebra: an expression which would seem to imply that other treatises were then already extant." So the earliest form of the claim carries the words "by a Mohammedan", and its editor reads the author's own preface as pointing to algebra already existing around him. Question: if the sentence kept the qualifier the manuscript note keeps ("first book written on algebra by a Muslim"), would it still say what this page intends it to say?