Person: AlJawhari, alAbbas ibn Said
AlJawhari was an Islamic mathematician whose main work was a commentary on Euclid's Elements.
Mathematical Profile (Excerpt):
 AlJawhari was employed in the service of alMa'mun in Baghdad, although we do not know exactly when he began his work there.
 AlJawhari, although best known as a geometer, made observations in Baghdad from 829 to 830 while working for alMa'mun.
 The main work by alJawhari was Commentary on Euclid's Elements which is listed in the Fihrist (Index), a work compiled by the bookseller Ibn anNadim in 988.
 Commentary on Euclid's Elements is almost the same work described by Nasir aldin alTusi (although alTusi gives a slightly different title for alJawhari's work: Emendation of the Elements).
 This work contained nearly fifty propositions additional to those given by Euclid and included an attempt by alJawhari to prove the parallel postulate.
 AlTusi quotes six of the nearly fifty propositions which together form what alJawhari believed was a proof of the parallel postulate.
 This means that, as far as we are aware, alJawhari was the first Arabic mathematician to attempt such a proof.
 In the short treatise alJawhari presents three additions to Book V of Euclid's Elements, which are meant prove Definition 5 which defines equal ratio, and Definition 7 which defines greater ratio.
 AlJawhari's "proofs" are examples of early attempts by Muslim mathematicians to understand the difficult concepts in Euclid's Elements.
Born about 800, possibly Baghdad, Iraq. Died about 860, possibly Baghdad, Iraq.
View full biography at MacTutor
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Ancient Arab, Origin Iraq
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Epochs: 1
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References
Adapted from other CC BYSA 4.0 Sources:
 O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive