Abū'l-Ḥasan ʿAlī ibn Muḥammad ibn ʿAlī al-Qurashī al-Qalaṣādī (; 1412–1486
) was a
Muslim
Muslims () are people who adhere to Islam, a Monotheism, monotheistic religion belonging to the Abrahamic religions, Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God ...
Arab
Arabs (, , ; , , ) are an ethnic group mainly inhabiting the Arab world in West Asia and North Africa. A significant Arab diaspora is present in various parts of the world.
Arabs have been in the Fertile Crescent for thousands of years ...
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
from
Al-Andalus
Al-Andalus () was the Muslim-ruled area of the Iberian Peninsula. The name refers to the different Muslim states that controlled these territories at various times between 711 and 1492. At its greatest geographical extent, it occupied most o ...
specializing in
Islamic inheritance jurisprudence.
Franz Woepcke stated that al-Qalaṣādī was known as one of the most influential voices in
algebraic notation for taking "the first steps toward the introduction of
algebra
Algebra is a branch of mathematics that deals with abstract systems, known as algebraic structures, and the manipulation of expressions within those systems. It is a generalization of arithmetic that introduces variables and algebraic ope ...
ic symbolism
''. He wrote numerous books on
arithmetic
Arithmetic is an elementary branch of mathematics that deals with numerical operations like addition, subtraction, multiplication, and division. In a wider sense, it also includes exponentiation, extraction of roots, and taking logarithms.
...
and algebra, including ''al-Tabsira fi'lm al-hisab'' ( "''Clarification of the science of arithmetic''").
Early life
Al-Qalaṣādī was born in
Baza, an outpost of the
Emirate of Granada
The Emirate of Granada, also known as the Nasrid Kingdom of Granada, was an Emirate, Islamic polity in the southern Iberian Peninsula during the Late Middle Ages, ruled by the Nasrid dynasty. It was the last independent Muslim state in Western ...
. He received education in
Granada
Granada ( ; ) is the capital city of the province of Granada, in the autonomous communities of Spain, autonomous community of Andalusia, Spain. Granada is located at the foot of the Sierra Nevada (Spain), Sierra Nevada mountains, at the confluence ...
, but continued to support his family in Baza. He published many works and eventually retired to his native Baza.

His works dealt with Algebra and contained the precise mathematical answers to problems in everyday life, such as the composition of medicaments, the calculation of the drop of irrigation canals and the explanation of frauds linked to instruments of measurement. The second part belongs to the already ancient tradition of judicial and cultural mathematics and joins a collection of arithmetical problems presented in the form of poetical riddles.
In 1480 the
Christian
A Christian () is a person who follows or adheres to Christianity, a Monotheism, monotheistic Abrahamic religion based on the life and teachings of Jesus in Christianity, Jesus Christ. Christians form the largest religious community in the wo ...
forces of
Ferdinand
Ferdinand is a Germanic name composed of the elements "journey, travel", Proto-Germanic , abstract noun from root "to fare, travel" (PIE , "to lead, pass over"), and "courage" or "ready, prepared" related to Old High German "to risk, ventu ...
and
Isabella, "The Catholic Monarchs", raided and often pillaged the city. Al-Qalasādī served in the mountain citadels which were erected in the vicinity of Baza. Al-Qalasādī eventually left his homeland and took refuge with his family in
Béja,
Tunisia
Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...
, where he died in 1486. Baza was eventually besieged by the forces of Ferdinand and Isabella and then sacked.
Symbolic algebra
Like his predecessors, al-Qalaṣādī used an
algebraic notation. While the 19th century writer Franz Woepcke believed that this algebraic symbolism was created by al-Qalaṣādī, these symbols had actually been used by other mathematicians in North Africa 100 years earlier.
[ Al-Qalaṣādī represented ]mathematical symbols
A mathematical symbol is a figure or a combination of figures that is used to represent a mathematical object, an action on mathematical objects, a relation between mathematical objects, or for structuring the other symbols that occur in a mathemat ...
using characters from the Arabic alphabet
The Arabic alphabet, or the Arabic abjad, is the Arabic script as specifically codified for writing the Arabic language. It is a unicase, unicameral script written from right-to-left in a cursive style, and includes 28 letters, of which most ...
, where:[
*ﻭ ('' wa'') means "and" for ]addition
Addition (usually signified by the Plus and minus signs#Plus sign, plus symbol, +) is one of the four basic Operation (mathematics), operations of arithmetic, the other three being subtraction, multiplication, and Division (mathematics), divis ...
(+)
*إلا ('' illa'') literally, "except"; means "less" for subtraction
Subtraction (which is signified by the minus sign, –) is one of the four Arithmetic#Arithmetic operations, arithmetic operations along with addition, multiplication and Division (mathematics), division. Subtraction is an operation that repre ...
(−)
*في (''fi'') literally, "in"; means "times" for multiplication
Multiplication is one of the four elementary mathematical operations of arithmetic, with the other ones being addition, subtraction, and division (mathematics), division. The result of a multiplication operation is called a ''Product (mathem ...
(*)
*على (''ala'') means "over" for division (/)
*ﺝ ('' j'') represents ''jadah'' meaning "root
In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often bel ...
"
*ﺵ ('' sh'') represents ''shay meaning "thing" for a variable (x)
*ﻡ ('' m'') represents ''maal'' for a square
In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...
(x2)
*ﻙ ('' k'') represents ''moka'aab'' for a cube
A cube or regular hexahedron is a three-dimensional space, three-dimensional solid object in geometry, which is bounded by six congruent square (geometry), square faces, a type of polyhedron. It has twelve congruent edges and eight vertices. It i ...
(x3)
*ﻝ ('' l'') represents ''ya'adilu'' for equality (=)
See also
* Islamic mathematics
* List of Muslim scientists
Notes
References
*
*
External links
*
{{DEFAULTSORT:Qalasadi, Abu Hasan Ali
1412 births
1486 deaths
15th-century Arab people
People from the Province of Granada
Mathematicians from al-Andalus
15th-century mathematicians
Jurisprudence academics
Mathematicians who worked on Islamic inheritance
Scholars of the Nasrid period
15th-century Spanish mathematicians