Scholar of mathematics and physics (B.11 October 1910, Kayalar / Thessaloniki – D.26 December 1997, Istanbul). He is a worldwide famous mathematician and physicist who was raised in the Republican Period of Turkey. At the age of two, his family settled to Istanbul since Thessaloniki came under control of Greek army during the Balkan War. At the age of four he started school in Istanbul. In 1919 at the age of nine he moved to Ankara with his family. His family left here and returned to Istanbul for a short period and then settled to Izmir. Cahit Arf’s interest in mathematics started in his Izmir years. While in primary school he understood the geometric proof of Pythagorean Theorem. Since the shape which was drawn for the evidence resembled the ears of a donkey, old generations called this theorem “donkey’s theorem”. It is known that his mathematics teacher encouraged Cahit Arf to solve questions from Euclidean geometry during his education in Izmir.
In 1926 his family decided that it was a more appropriate option for him to receive an education a good education. Thus, Cahit Arf was sent to France for high school education in 1926. After his high school education he completed in France, Ecole Normale Superieure in 1932 he wanted to be appointed teacher in Kastamonu High School. However, with the help and direction of his environment he served as a mathematics teacher in Galatasaray High School for a while and later within the reform of universities in 1933 he was assigned as a candidate associate professor to Istanbul University Faculty of Science.
Cahit Arf worked together with his teacher Hasse to advance in his career at Göttingen University in Germany, to where he was sent in 1937 to complete his PhD program. As a result of this effort he completed his PhD thesis in 1938 which also contained the famous result which is known as “Hasse-Arf Theorem” in mathematics. In 1938, Cahit Arf essentially contributed to mathematics with his studies in various fields such as algebra, number theory, theory of elasticity, analysis, geometry and engineering mathematics and acquired structural and permanent results. Upon the insist of Hasse he stayed for one more year in Germany to continue his studies and meanwhile he discovered “Arf Invariants” which was a great contribution to mathematics. His first scientific study was published in a famous mathematics journal of Germany “Crelle Journal”in 1939.
After returning to Turkey he became a professor in Istanbul University Faculty of Science in 1943. Cahit Arf classified quadratic forms on objects whose characteristics were two in a very skillful way. He built their invariants. These invariants are known in the world literature as “Arf Invariants”. This study of him was published in “Crelle” journal in 1944and introduced Cahit Arf to the world. He was promoted to distinguished professorship in 1955 and he worked in Istanbul University until 1962. In 1963 he started to give mathematics lessons in Robert College. In 1964 he became President of the Scientific Branch of Turkish Scientific and Technical Research Institution (TÜBİTAK). In 1966 he went to United States of America and worked in Universities of Princeton and California. In 1967 he returned to Turkey and started to work at Middle Eastern Technical University. He played a very effective role in the establishment of TÜBİTAK, Turkish Scientific and Technical Research Institution. He took part in the establishment of Marmara Research Center in Gebze.
Cahit Arf retired in1980 from his duty at the university and served in Gebze Research Center which is connected to TÜBİTAK. Between the years 1985 and 1989 he presided Turkish Mathematics Association. He inspired all Turkish mathematicians directly or indirectly, expanded the horizons of all mathematicians around him with his warnings and ideas and made it possible for them to direct their studies in a new perspective.
While working at the Middle East Technical University he proved multiple times that he was not a scientist detached from the world. It is known that Cahit Arf was reconciliatory but a principled scientist who did not make concessions from his scientific personality. With his studies about algebra he became famous in the whole world. His studies about solubility of synthetic geometrical problems using a ruler and compasses, and studies about invariants which appear during the classification of quadratic forms of objects which are known after his name as "Arf Invariant" or "Arf Rings", made him known among the famous mathematicians in the world of mathematics. The formula of “Arf Invariant” is as following: arf (g)=n Sigmaİ=1 q(a;) q(b;)E Z2. Cahit Arf regarded mathematics not as a profession but as a lifestyle. He always said to his students: “Don’t memorize mathematics, do it yourself and understand it.”.
He introduced to the literature of mathematics not only with concepts of "Arf Rings”, “Arf Invariants” and “Arf Closure", but also theorems which are known as "Hasse-Arf Theorem". Cahit Arf, who entered the literature of world mathematics with his "Arf Theorem" and was accepted as “Einstein of Turkey”, is one of our rare talents who evaluated science who became a model for scientific and academic communities by using his research intelligence.
During the last years he studied about the possible applications of mathematics within the science of biology. In 1948 he received the İnönü Award. In 1974 he was granted the TÜBİTAK Science Award, the Honorary PhD by İTÜ and KTÜ in 1980 and the Honorary PhD by ODTÜ (METU) in 1981. At a young age, he was chosen to Mainz Academy Informative Member and he became Honorary Member of Turkish Sciences Academy. France presented him in 1994 “Commandeur des Palmes Academique Prix”. In the words of Prof. Dr. Gündüz İkeda, a Turkish mathematician with Japanese origin, “Cahit Arf, is the most skillful mathematician Turkey has had until now.” In the backside of 10 Turkish Lira, a portrait of Dist. Prof. Dr. Cahit Arf is present. Aside from a section from Cahit Arf’s “Arf Invariant”, the backside of 10 Turkish Lira is filled with elements such as “arithmetic series, abacus, digits which express binary number system which indicate the digital system which is the basis of computer technology”.
Besides being the Pioneer of mathematics fort he last fifty years of our country, Cahit Arf became the “teacher of teachers” whom his young colleagues approached for advice and experience and modeled his determined and strong minded personality at hard times with his interest in social problems, loyality to his country, sensitivity about the problems of the university and education in general. He never abstained from saying clearly what he knew as true. He wrote numerous articles about his field and held many conferences at home and abroad. Cahit Arf also has a published book titled ‘Anlamak’ Tutkunu Bir Matematikçi (common, 2006).
REFERENCE: A. Dönmez / Matematik Tarihi (1986), Milliyet Büyük Larousse Ansiklopedisi (1986, c. 2. s. 776), Ali Sinan Sertöz / “Cahit Arf; Bir Efsanenin Ardından” (Bilim ve Teknik, sayı: 364, 1998), Ersan Akyıldız / Hocaların Hocası Cahit Arf (Bilim ve Ütopya, s. 137 / 2005, s. 21-28), Gökhan Tok / Cahit Arf: Matematikle Geçen Bir Ömür (Liderler-1, 1996, s. 112-116), Niyazi Hüseyin Bahtiyar / Balkanlar’da Türk Ünlüleri (1999, s.73-75), İsmihan Yusubov / Ünlü Bir Matematikçi Hakkında Etüt-Esse Cahit Arf Sonsuzluğu (Bilim ve Ütopya sayı.103, s.32-33, 2003), Ferhat Dinçer / Harezmî'den Cahit Arf'a (2008), İhsan Işık / Ünlü Bilim Adamları (Türkiye Ünlüleri Ansiklopedisi, C. 2, 2013) - Encyclopedia of Turkey’s Fomous People (2013).