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Person: Al Qalasadi, Abu'l Hasan ibn Ali

Al-Qalasadi was a Spanish Islamic mathematician who took the first steps toward the introduction of algebraic symbolism by using letters in place of numbers.

Mathematical Profile (Excerpt):

• The Christian kingdom of Castile to the north had suffered civil strife through the 14th Century, so Andalusia had prospered but, in 1407, five years before al-Qalasadi was born, Castile began a major push to conquer the whole of Spain and Portugal.
• Al-Qalasadi was a Muslim who was brought up in Bastah which is north-east of Granada city.
• Al-Qalasadi began his education in Bastah, studying law, the Qur'an and the science of fixed shares in an estate.
• Al-Qalasadi chose to remain in the Islamic world and he left Granada and travelled widely throughout Islamic territory.
• Form there al-Qalasadi went to Egypt where again he studied with some of the leading scholars.
• Eventually al-Qalasadi reached Mecca, the purpose of his pilgrimage, and returned to Granada.
• Things were in a bad way when al-Qalasadi returned to Granada.
• However, al-Qalasadi taught and wrote some of his major works during this period but eventually the advancing Christian armies made life impossible for him.
• The defeat of the whole Muslim state in Granada finally took place until 1492, six years after al-Qalasadi's death in North Africa, when the city of Granada fell to Christian Castile.
• Ibn al-Banna was a Moroccan who had died over 100 years before al-Qalasadi wrote his commentary but, perhaps surprisingly, ibn al-Banna himself had written a commentary on his own work.
• Certainly al-Qalasadi wrote original works.
• This was a difficult text and, perhaps to some extent following the example of ibn al-Banna, al-Qalasadi followed it up by writing a simpler version which he called Unveiling the science of arithmetic.
• Both of the simpler versions of al-Qalasadi's arithmetic treatise proved popular in teaching arithmetic in North Africa and the works were in use for over 100 years.
• It is now certain that, despite being popular teaching books, there was little original in al-Qalasadi's work.
• The difficulty was that al-Qalasadi, being one of the last of the mathematicians associated with the major mathematical contributions by the Muslims and Arabs, was better known than many of the earlier contributors.
• Ignorance of the earlier contributions led historians to give too much credit to al-Qalasadi whom in many ways displayed the same characteristics as the later ancient Greek mathematicians.
• This leads him to stress the importance of the algebraic symbolism used by al-Qalasadi (1412-1486) without taking into consideration similar previous attempts both in Eastern and in Western Islam, a fact which was already known - in the second half of the 19th century - by F Woepcke.
• 1321, a Moroccan) and al-Qalasadi (d.
• Certainly symbols were not the invention of al-Qalasadi.
• We should not, however, let any of this argument detract from al-Qalasadi's contribution.

Born 1412, Bastah (now Baza, Spain). Died 1486, Béja, Tunisia.

View full biography at MacTutor

Tags relevant for this person:

Ancient Arab, Origin Spain

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@J-J-O'Connor

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References

Adapted from other CC BY-SA 4.0 Sources:

1. O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive