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Giyaseddin Ebu'l Feth Bin İbrahim El Hayyam

Mathematician, astronomer, philosopher, poet
(B. Nishapur, / Persia, 18^{th}
May 1048 – D. Nishapur 4^{th} December 1131) He was a well-known
mathematician, scholar and poet from Persia under the Seljuk rule. Even though
available knowledge about his life is not reliable, the importance of those
sources should not be underestimated. Omer Khayyam’s full name was Giyaseddin
Ebu'l Feth Bin İbrahim El Hayyam and he was the son of a tentmaker. His byname,
meaning tentmaker, was derived from his father’s profession. His family was
from the Town of Nishapur or from its vicinity. He was already famous as
mathematician when he was invited, by Malik-Shah I, to work together with Abu
el-Muzaffar İsfizâri and Maymûn b. Nacib el Vâsiti in readjustment of *Persian
Calendar* in 1074-75. He was regarded as the greatest polymath of the East
after Avicenna while he was still alive. It was said that Omar Khayyam, who had
important works on medicine, physics, astronomy, algebra, geometry, higher
mathematics and poetry, knew all the learning of his time. Unlike everyone, he
didn’t put down most of his works on paper, yet he was the real inventor of the
most of theorems we heard of today.

After he completed his education, he wrote *Cebir
Risaliyesi* (al-Cebir) and *Rubaiyat,* which brought his reputation up
to today, in Samarkand. Three famous people of
that era, Nizam al-Mulk, Hasan-i Sabbah and Omer Khayyam came together in that
city. Malik-Shah I, the Padishah of that era, trusted his vizier Nizam al-Mulk
, whose name meant good order of the kingdom and who lived fulfilling his name,
very much. Nizam al-Mulk, who met Omer Khayyam in Samarkand, first invited him
to Isfahan. When they met there, he spoke of the kingdom and he asked Omer
Khayyam to help him make his dreams about the kingdom come true. Yet, Omer
Khayyam didn’t want to involve in the state affairs and he rejected him. He
wanted to stay away from tricks in the palace until his death and he moved to
Samarkand, Bukhara and Isfahan, which were the centers for science of that era,
to expand his knowledge. He died on 4^{th} December 1131 in Nishapur
where he was born.

Omer Khayyam, well known in the
world of mathematics for his works on Euclid’s parallel postulate, is also
famous as the poet of *Rubaiyat* in our country and in the Western world
with the interpretation of Fitzgerald (1859). Interest in Khayyam is highly
intense. For instance, having submitted intellectual and artistic achievement
of Persian culture in his study called *History of Western Philosophy*;
Bertrand Russell spoke highly of Khayyam and regarded him as “the sole person
he knew as both mathematician and poet.” The reprints of Omer Khayyam’s works
in recent years have confirmed the importance of his mathematical studies.
Currently, his mathematical works are reviewed in three categories. 1)
Formulation of basic algebraic geometry, 2) Studies on theory of
proportionality, 3) Studies on theory of parallels. Thanks to the new findings
mentioned above, it was understood that Omer Khayyam’s mathematical works were
far more important than it had been thought before. United Nations Educational,
Scientific and Cultural Organization (UNESCO), arranged an international
colloquium in 1999 to celebrate Khayyam’s achievements and decided to print
Khayyam’s important mathematical works. Within the scope of UNESCO’S project
called “Beyt-ül Hikme” Roshdi Rashed, a well-known Egyptian historian of
science, who lives in Paris and Bijan Vahabzadeh, who is known for his
doctorate on Omer Khayyam, took on the task of critical edition of Khayyam’s
important manuscripts about mathematics, some of which were known and some not
known then. That critical edition was first printed in French and then in
English.

Even though the information about
Khayyam’s life is very limited, it is known that he left a certain number of
philosophic works behind. Khayyam is also matched with a Persian poet of *Rubaiyat,
*who was an incognito but well respected. The question of who wrote *Rubaiyat*
raised issues between historians and historians of mathematics.

Rashed says *“to the best of my belief, we lack of the information which will help
us identify those two geniuses (poet and mathematician). None of the
information given by historians such as Beyhaki, Arudi, Sefadi, İbn-ül Esir
about the mathematician Khayyam does mention about the poet Khayyam; on the
other hand, the ones who mention about poet does not speak of any
mathematician”*. According to Rashed, association of poet Khayyam and
mathematician Khayyam occurred long after the composing of *Rubaiyat*. It
is controversial whether the composer of *Rubaiyat* and mathematician and
philosopher Khayyam was the same person or not.

The writers,
mentioned above, compares Descartes’ work called *Geometry* and his other
works to Khayyam’s works. They claim that Descartes’ works on algebraic
equation of geometric theory should be regarded as the complement of Khayyam’s
works, by emphasizing that Descartes’ works should be reviewed in the view of
Khayyam’s and Tusi’s works .

After all, the
book does not only enlighten works of a Muslim mathematician but also
enlightens the progress of early period modern mathematics. Without this work,
the historian would not completely understand the works of Descartes and would
misjudge the birth of modern science which changed the world. UNESCO,
which contributed a great deal to our understanding of history of mathematics
by taking on an edition of Khayyam’s works, should be thanked. Works of Rashed
and Bahabzadeh emphasized that, we shouldn’t consider mathematician Khayyam and
poet Khayyam as the same person unquestioningly.

Omer Khayyam also did scientific researches by
observing the sky in his observatory which he built in three years in Isfahan.
He, himself, detected his own birth date so precisely with the help of
astronomers’ accuracy. Omer Khayyam, who was invited to Merv by Sultan
Celalettin Malik-shāh, was the leader of a panel formed to establish a new
calendar. He made a great effort for the calendar, colloquially known as *“Omer
Khayyam Calendar*” but today known as *“Jalali Calendar*”*.* While
that calendar using the solar year leads to an error of 1 day in 5000 days, the
*“Gregorian Calendar” *we use today leads to an error of 1 day in 3330
years. It shows how Khayyam’s knowledge of astronomy was further than his era.

According to a rumor about the usage of the letter
“X” to denote unknowns in mathematics, Omer Khayyam indicated unknowns as “şey”
in equation while he studied on algebraic in Samarkand. That word was written
as “xey” in Spanish works in Andalusia and in time it took the form of “X” and
then it became universal letter “X” to denote unknowns.

**WORKS:**

*Ziyc-i
Melikşahi*
(About astronomy and calendar), *Kitabün
fi'l Burhan ül Sıhhat-ı Turuk ül Hind* (About geometry), *Risaletün fi Berahin İl Cebr ve Mukabele*
(About algebraic and equation), *Müşkilat'ül
Hisab* (About arithmetic), *İlm-i
Külliyat* (About general principles), *Nevruzname*
(About calendar and detection of new year beginning), *Risaletün fil İhtiyal li Marifet* (About detection of volume of gold
and silver in golden and silver items), *Risaletün
fi Şerhi ma Eşkele min Musaderat* (About method of solving Euclidean
problem), *Risaletün fi Vücud* (About
ontology in philosophical), *Muhtasarun
fi't Tabiiyat* (About science of physic), *Risaletün fi'l Kevn vet Teklif* (About philosophy), *Levazim'ül Emkine* (About climates of
residence areas and changes in the
weather), *Fil Cevab Selaseti Mesâil ve fi
Keşfil Hicab* (Answer to three matters and about necessity of polar
opposites in the universe ), *Mizan'ül
Hikem *( about knowing the values of diamond jewelry without extracting its
diamonds ), *Abdurrahman'el Neseviye Cevab*
(about manifestation of Allah in forming universe and in obligation of
prayers), *Nizamülmülk* (A biography of
a vizier, his friend), *Eş'arı bil
Arabiyye* (Rûba in Arabic, T.N.: Arabian quatrain), *Fil Mutayat* (About principles of science).

REFERENCE:
Rıza Tevfik Bölükbaşı / Ömer
Hayyam’ın Felsefesi (1919),* *Hüsey,n
Rıfat / Ömer
Hayyam: Manzum Rubâî Tercemeleri
(1943), Ömer Rıza Doğrul /
Ömer Hayyam* *(Harold Lamb’dan, 1944),
Vasfi Mahir Kocatürk / Ömer Hayyam’dan
Rubailer (1955), İslâm
Ansiklopedisi (1964), Rashed ve Roshdi / Batılı Bilim Nosyonu: “Batılı Bir
Görüngü Olarak Bilim” (Çev. Bekir S. Gür, 1994), Bertrand Russell / A History of Western
Philosophy (2. Basım 2004), Çeşm-i Şarâbât’ta Yıldızlar (Ömer
Hayyam’dan çeviri şiirler, 2004), İhsan Işık / Ünlü Bilim Adamları (Türkiye Ünlüleri
Ansiklopedisi, C. 2, 2013) - Encyclopedia of Turkey’s Famous People (2013).