Yusuf al-Mu'taman ibn Hud

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Yusuf al-Mu'taman Billah
Ruler of
Al-Mustain II
BornZaragoza
Died1085
Names
al-Mu'taman Billah Abu Amir Yusuf ibn Ahmad ibn Hud
HouseBanu Hud

Abu Amir Yusuf ibn Ahmad ibn Hud (

Arabic: المؤتمن بالله, romanized: al-Mūʾtaman bi-ʾLlāh, lit.
 'Trustee through God').

Al-Mu'taman was the third king of the Banu Hud dynasty, reigning from 1081 to 1085, at the height of power of Muslim Zaragoza, following the thriving period of his father Ahmad al-Muqtadir. He continued his father's efforts and created around him a court of intellectuals, living in the beautiful palace of Aljafería, nicknamed as "the palace of joy".

As king, Al-Mu'taman was a patron of science, philosophy and arts, and was himself a scholar of considerable accomplishment. He knew astrology, philosophy, and especially mathematics, a discipline in which he wrote the most important treatise to come out of the al-Andalus region in the 11th century,[1] the Kitab al-Istikmal ("Book of Perfection").

Biography and Kingship

Yusuf was born on an unknown date, certainly in Zaragoza, in the palace of

Lérida, Monzón, Tortosa and Dénia
.

The first external concern of the king was the threat posed by the

Alfonso VI for conducting raids against his interests in the Taifa of Toledo
, then a tributary of the king. In 1081, El Cid therefore offered his service to the king of Zaragoza, al-Muqtadir, and remained with al-Mu'taman during his reign.

Al-Mu'taman also assigned to El Cid the task of reincorporating into Zaragoza the eastern territories of his relative Mundhir, an ally of Aragon. Clashes in the border area were constant, but neither managed to reunite the paternal territory.

El Cid contained the attacks of the Aragonese until 1083, when Sancho managed to take the line of fortifications that protected Zaragoza like Graus in the east, as well as Ayerbe, Bolea, Arascués and Arguedas. El Cid served Yusuf al-Mu'tamin until 1086, when he broke his ties with Zaragoza. The circumstances in which he refused to continue serving al-Mu'tamin and his heir Ahmad II al-Mustaʿin are not fully clear and still debated.

Al-Mu'taman also tried to strengthen relations with his vassal king of Valencia, Abu Bakr, through marriage alliances. But Valencia was entangled in a complex game of alliances. Alfonso VI, skilfully using diplomacy, got al-Kadir, the king of Toledo, to hand over the city in 1085 in exchange for his help to drive Abu Bakr from Valencia, which meant, in fact, the capture of Toledo for the king of Castile. Thus, the kingdom of Zaragoza was cut off from the rest of al-Andalus, which seriously weakened its economy and made it even more vulnerable to Christian attacks. The year of the loss of Valencia was also the year of the death of Yusuf al-Mu'tamin.

Intellectual life

Although it was common practice for royals to be well educated, both al-Mu'taman and his father were exceptional mathematicians. In medieval Islam, there was a

Ibn Qurra
and al-Mu'taman offered their own input and original contributions beyond their transmission of ancient ideas.

Mathematics

Ceva's theorem, discovered at the end of the 11th century by al-Mutaman.

The main work of al-Mu'taman was his Kitab al-Istikmal (Book of Perfection). This book was a compendium of the Greek mathematics of

Thabit ibn Qurra, the Banu Musa and Ibn al-Haytham, and included some theorems and proofs not found in earlier extant sources. The book only persists as fragments from several anonymous manuscripts, not including any preface or introduction, but it is clear from the remaining content that the intention was to organize and comprehensively describe the known results in Euclidean geometry in a single self-contained work.[2] It is possible al-Mu'taman listed his sources in a now-lost introductory section, but none of the remaining fragments credit past authors or works for any of the content.[2]

The Kitab al-Istikmal was not completed but it was still seen as an important work from the eleventh-century king. The encyclopedist

Ibn Aknin suggested that the Istikmal should be read by mathematicians alongside such works as the Elements of Euclid, On the Sphere and Cylinder of Archimedes, and Conics of Apollonius. Because this was not a completed piece of work it was never as widely copied or taught as the works of Euclid or Archimedes. A copy was sent to Egypt by Maimonides, and from there it spread to Baghdad in the 14th century, but did not directly influence later European mathematicians.[citation needed
]

The Kitab al-Istikmal deals with

stereometry
.

The Kitab al-Istikmal contains the first known formulation of Ceva's theorem, which only became known in Europe after 1678 from Italian geometer Giovanni Ceva's treatise De lineis rectis. It is unknown whether Al-Mu'taman discovered this theorem himself or obtained it from another source, and it is also unknown whether Ceva rediscovered the theorem independently.[3] The theorem can be stated as follows: "Let ABC be a triangle and D, E, F points on the sides BC, CA, and AB. We draw the lines AD, BE and CF. These three lines intersect at one point if and only if .

See also

  • List of Arab scientists and scholars

References

  1. ^ Glick, Thomas F.; Livesey, Steven John; Wallis, Faith (2005). Medieval Science, Technology, and Medicine: An Encyclopedia. Psychology Press. p. 243.
  2. ^
    doi:10.1016/0315-0860(86)90227-2.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  3. ISBN 3-642-14440-3
    .

External links

Preceded by King of Zaragoza
1081-1085 		Succeeded by
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