The reasonable man adapts himself
to the world; the unreasonable one persists in trying to adapt the world to
himself. Therefore, all progress depends on the unreasonable man.

George
Bernard Shaw

- Education
- Scholarships
- Professional Experience
- Courses Taught
- Topics for Student
Projects and Theses
- Languages
- Selected Publications
- On Screen
- Some Photos
- "Dijital Deliller" duyurusu - 2013
- "30 Mart Seçimleri"
- Yeni "Dijital Deliller" duyurusu 6.5.2014

I am a professor of computer science in Boğaziçi University. My research interests are Theoretical Computer Science and Artificial Intelligence.

I am also a science writer, with articles in *Herkese Bilim Teknoloji* magazine, and
the author of the popular book *50 Soruda
Yapay Zekâ*.

In "civilian" life, I am known as an overall nice guy with a liking for science fiction, Western languages, and all kinds of funny things.

**Full Name:**

Ahmet Celal Cem Say

**Date and Place of Birth:**

p Day, 1966, Ankara

**Nationality:**

Turkish

**Address:**

Boğaziçi University, Department of Computer Engineering, Bebek, 34342, İstanbul, Turkey.

**Phone:**

+90-212-3596628

**Fax:**

+90-212-2872461

**Email:**

say at boun dot edu dot tr

**Erdös Number:**

at most 3

- T.E.D. Ankara High School (1983)
- B.S. in
*Computer Engineering*from Boğaziçi University (1987) - Ph.D. in
*Computer Engineering*from Boğaziçi University (1992) - Turkish Army School of
*Communications, Electronics and Information Systems*(1995)

- High school scholarship of TÜBİTAK (Turkish Scientific & Technological Research Institution)
- Ph.D. scholarship of TÜBİTAK
- University of Vienna Language School Scholarship
- Italian Institute of Culture Language School Scholarship

- 1987-1992 Boğaziçi University, Department of Computer Engineering, Research Assistant.
- 1995-1996 Turkish Naval Inventory Control Center Command, Supply Services Software Officer.
- 1992-1996 Boğaziçi University, Department of Computer Engineering, Assistant Professor.
- 1996-2003 Boğaziçi University, Department of Computer Engineering, Associate Professor.
- 2003-... Boğaziçi University, Department of Computer Engineering, Professor.

(I have been seen in Işık, Galatasaray, and Bilgi Universities as well.)

- Introductory Computing & Programming,
- Java,
- Discrete Computational Structures,
- Formal Languages and Automata Theory,
- Introduction to Artificial Intelligence,
- Natural Language Processing,
- Theory of Computation,
- Probabilistic and Quantum Finite Automata,
- Advanced Topics in Theoretical Computer Science,
- Quantum Algorithms,
- Qualitative Reasoning,
- Complexity Theory.

- Turkish,
- English,
- German,
- French,
- Italian,
- Spanish,
- Azeri. (well, all Turks understand it.)

- A. C. Cem Say, Selahattin
Kuru, "Improved
filtering for the QSIM algorithm,"
*IEEE Transactions on Pattern Analysis and Machine Intelligence*Vol. 15, pp. 967-971, 1993. - A. C. Cem Say, Selahattin
Kuru, "Qualitative
system identification: Deriving structure from behavior,"
*Artificial Intelligence*Vol. 83, pp. 75-141, 1996. - A. C. Cem Say, Selahattin
Kuru, "Postdiction using reverse qualitative simulation,"
*IEEE Transactions on Systems. Man, and Cybernetics**Part A: Systems and Humans*Vol. 27, pp. 84-95, 1997. - A. C. Cem Say,
"L'Hôpital's filter for QSIM,"
*IEEE Transactions on Pattern Analysis and Machine Intelligence*Vol. 20, pp. 1-8, 1998. - A. C. Cem Say, "Making
use of contradictory behavior information in qualitative reasoning,"
*IEEE Transactions on Pattern Analysis and Machine Intelligence*Vol. 21, pp. 781-786, 1999. - A. C. Cem Say, "Understanding
arithmetic problems in Turkish,"
*International Journal of Pattern Recognition and Artificial Intelligence*Vol. 15, pp. 359-374, 2001. - A. C. Cem Say,
"Improved reasoning about infinity using qualitative
simulation,"
*Computing and Informatics*Vol. 20, pp. 487-507, 2001. - A. C. Cem Say,
"Problems in representing liquid tanks with monotonicity constraints:
A case study in model-imposed limitations on the coverage of qualitative
simulators,"
*Artificial Intelligence Review*Vol. 17, pp. 291-317, 2002. - A. C. Cem Say, "Sound and complete
qualitative simulation requires "quantitative" filtering,"
*Annals of Mathematics and Artificial Intelligence*Vol. 38, pp. 257-267, 2003. - Tolga Könik, A. C. Cem Say, "Duration
consistency filtering for qualitative simulation,"
*Annals of Mathematics and Artificial Intelligence*Vol. 38, pp. 269-309, 2003. - A. C. Cem Say, H. Levent
Akın, "Sound and complete
qualitative simulation is impossible,"
*Artificial Intelligence*Vol. 149, pp. 251-266, 2003. - A. C. Cem Say, A. Kutsi
Nircan, "Random generation of monotonic functions for Monte Carlo solution
of qualitative differential equations,"
*Automatica*Vol. 41, pp. 739-754, 2005. - Özgür Yılmaz, A. C. Cem Say, "Causes of ineradicable
spurious predictions in qualitative simulation,"
*Journal of Artificial Intelligence Research*, Vol. 27, pp. 551-575, 2006. - Abuzer
Yakaryılmaz, A. C. Cem Say, "Efficient probability amplification in
two-way quantum finite automata,"
*Theoretical Computer Science*, Vol. 410, pp. 1932-1941, 2009. (doi:10.1016/j.tcs.2009.01.029) - Rūsiņš Freivalds, Abuzer
Yakaryılmaz, A. C. Cem Say, "A new family of nonstochastic
languages,"
*Information Processing Letters*, Vol. 110, pp. 410-413, 2010. doi: 10.1016/j.ipl.2010.03.011 - Abuzer Yakaryılmaz, A. C.
Cem Say, "Languages recognized by nondeterministic quantum finite
automata,"
*Quantum**Information and Computation*, Vol. 10, pp. 747-770, 2010. - Abuzer Yakaryılmaz, A. C. Cem Say,
"Succinctness of two-way probabilistic and quantum finite
automata,"
*Discrete Mathematics and Theoretical Computer Science*, 12(4), pp.19-40, 2010. - Abuzer Yakaryılmaz, A. C. Cem Say,
"Unbounded-error quantum computation with small space bounds,"
*Information and Computation*, Vol. 209, pp.873-892, 2011. [slightly older version at arXiv:1007.3624] - Abuzer Yakaryılmaz, Rūsiņš Freivalds, A. C. Cem Say,
Ruben Agadzanyan, "Quantum computation with write-only memory,"
*Natu**ral Computing*, Vol. 11, pp.81-94, 2012. doi: 10.1007/s11047-011-9270-0 - A. C. Cem
Say, Abuzer Yakaryılmaz, "Computation with multiple CTCs of fixed
length and width,"
*Natural Computing*, Vol. 11, No. 4, pp. 579-594, 2012. doi: 10.1007/s11047-012-9337-6 (errata) - A. C. Cem
Say, Abuzer Yakaryılmaz, "Quantum counter automata,"
*International Journal of Foundations of Computer Science*, Vol. 23, No. 5, pp. 1099-1116, 2012. doi: 10.1142/S012905411250013X - Abuzer
Yakaryılmaz, A. C. Cem Say, "Proving the power of
postselection,"
*Fundamenta**Informaticae*, Vol. 123, No. 1, pp. 107-134, 2013. - Abuzer
Yakaryılmaz, A. C. Cem Say, "Tight bounds for the space complexity of
nonregular language recognition by real-time machines,"
*International Journal of Foundations of Computer Science*, Vol. 24, No. 8, pp. 1243-1253, 2013. DOI. - A. C. Cem Say, Abuzer
Yakaryılmaz, "Finite
state verifiers with constant randomness,"
*Logical Methods in Computer Science*, Vol. 10(3:6)2014, pp. 1-17. (errata) - Uğur
Küçük, A. C. Cem Say, Abuzer Yakaryılmaz, "Finite automata with advice tapes,"
*International Journal of Foundations of Computer Science*, Vol. 25, No. 8, pp. 987-1000, 2014. - H. Gökalp Demirci, A. C.
Cem Say, Abuzer Yakaryılmaz, "The complexity of debate checking,"
*Theory of Computing Systems*, Vol. 57, pp. 36-80. DOI 10.1007/s00224-014-9547-7, 2015. http://eccc.hpi-web.de/report/2014/016 - Abuzer Yakaryılmaz, A. C.
Cem Say, H. Gökalp Demirci, "Debates with small transparent quantum
verifiers,"
*International Journal of Foundations of Computer Science*, Vol. 27, No. 2, pp. 283-300, 2016. arXiv: 1405.1655 - Özlem
Salehi, A. C. Cem Say, Flavio D’Alessandro, "Homing vector
automata,"
*RAIRO-Theor. Inf. Appl.*, Vol. 50, pp. 371–386, 2016. - A. C. Cem Say, Abuzer
Yakaryılmaz, “Magic coins are useful for small-space quantum
machines",
*Quantum Information & Computation*17.11&12 (2017), pp. 1027-1043. - Uğur Küçük, A. C. Cem Say,
Abuzer Yakaryılmaz. “Inkdots as advice for finite automata”,
*Discrete Mathematics and Theoretical Computer Science*Vol. 19:3, 2017, #1. - Ryan
O’Donnell, A. C. Cem Say, "The weakness of CTC qubits and the power of
approximate counting,"
*ACM Transactions on Computation Theory*Vol. 10:2, #5, 2018. - Özlem Salehi, Flavio
D’Alessandro, A. C. Cem Say, “Language
classes associated with automata over matrix groups”
*RAIRO-Theor. Inf. Appl.*, Vol. 52, pp. 253–268, 2018. - Gökalp Demirci, Mika Hirvensalo, Klaus Reinhardt, A. C. Cem Say, Abuzer
Yakaryılmaz, “Alternating, private alternating, and quantum alternating
realtime automata,”
*Logical Methods in Computer Science*, Volume 15, Issue 3, 2019, pp. 22:1–22:21 - Özlem Salehi, Abuzer Yakaryılmaz, A. C. Cem Say, "New
results on vector and homing vector automata,"
*International Journal of Foundations of Computer Science*, Vol. 30, No. 8, pp. 1335-1361, 2019.

- A. C. Cem Say, Selahattin
Kuru, "Nitel model tanılama," (in Turkish) Bilkon-91 1991
*Bilkent Elektrik-Elektronik ve Bilgisayar Mühendisliği Konferansı*, Ankara, 1991, pp. 363-366. - A. C. Cem Say, Selahattin
Kuru, "Qualitative system identification,"
*Lecture Notes in Control and Information Sciences*Vol. 180, (*System Modeling and Optimization: Proceedings of the 15th IFIP Conference, Zürich, Switzerland, September 2-6, 1991*),1992, pp. 657-666. - A. C. Cem Say, Selahattin
Kuru, "An extension of the corresponding value technique in
qualitative modeling and simulation,"
*Birinci Türk Yapay Zeka ve Yapay Sinir Ağları Sempozyumu*, Ankara, 1992, pp.23-28. - A. C. Cem Say, Selahattin
Kuru, "QSI: Constructing models for qualitative simulation,"
*Advances in Simulation '92 Symposium*, Boğaziçi Univ., İstanbul, 1992, pp. 37-46. - A. C. Cem Say, Selahattin
Kuru, "Automatic construction of qualitative models," in
*Intelligent Systems: Safety, Reliability, and Maintainability Issues*, Springer-Verlag, Berlin, 1993, pp. 177-193. - Cem Say, Sidal Sen, Ruhver
Barengi, "'Bir Kelime - Bir İşlem' oynayan program," (in
Turkish)
*İkinci Türk Yapay Zeka ve Yapay Sinir Ağları Sempozyumu*, İstanbul, 1993, pp. 349-355. - İlan Berker, A. C. Cem Say,
"A crossword puzzle generator for Turkish,"
*Proceedings of the Eighth International Symposium on Computer and Information Sciences (ISCIS-VIII)*, İstanbul, 1993, pp. 474-477. - Çiğdem Aytekin, A. C. Cem
Say, Erkut Akçok, "ELIZA speaks
Turkish: A conversation program for an agglutinative language,"
*Üçüncü Türk Yapay Zeka ve Yapay Sinir Ağları Sempozyumu*, Ankara, 1994, p. 435. - A. C. Cem Say, "Türkçe
'anlayan' programlar," (in Turkish)
*TBD Bilişim '94*, İstanbul, 1994, pp. 191-195. - Metin Örsel, A. C. Cem Say,
"Representing descriptions of flags,"
*Proceedings of the Ninth International Symposium on Computer and Information Sciences (ISCIS-IX)*, Antalya, 1994, pp. 575-582. - Müjdat Pakkan, A. C. Cem
Say, "Qualitative collision detection in the roller coaster
world,"
*Proceedings of the Ninth International Symposium on Computer and Information Sciences (ISCIS-IX)*, Antalya, 1994, pp. 583-590. - Murat Işık, A. C. Cem Say,
"Qualitative noise filtering and the implementation of QF as a
preprocessor to QSI,"
*Proceedings of the Tenth International Symposium on Computer and Information Sciences (ISCIS-X)*, Aydın, 1995, pp. 145-152. - A. C. Cem Say, "Functions
representable in pure QSIM,"
*Beşinci Türk Yapay Zeka ve Yapay Sinir Ağları Sempozyumu*, İstanbul, 1996, pp. 251-255. - A. C. Cem Say, "Qualitative
timeline analysis," in
*New Trends in Artificial Intelligence and Neural Networks*. EMO Scientific Books, Ankara, 1997, pp. 121-126. - F. Canan Pembe, A. C. Cem
Say, "A linguistically motivated information retrieval system for
Turkish,"
*Lecture Notes in Computer Science*Vol. 3280, (*Proceedings of the Nineteenth International Symposium on Computer and Information Sciences*), 2004, pp. 741-750. - Uğur Küçük, A. C. Cem Say, "Improved simulation
of quantum random walks,"
*Lecture Notes in Computer Science*Vol. 3733, (*Proceedings of the Twentieth International Symposium on Computer and Information Sciences*), 2005, pp. 937-946. - Abuzer Yakaryılmaz, Rūsiņš Freivalds, A. C. Cem Say, Ruben
Agadzanyan, "Quantum computation with devices whose contents are
never read,"
*Lecture Notes in Computer Science*Vol. 6079, (*Proceedings of the 9th International Conference on Unconventional Computation)*, 2010, pp. 164-174. [doi:10.1007/978-3-642-13523-1_18] - Nuri Taşdemir, A. C. Cem Say, "Models of pushdown
automata with reset,"
*Lecture Notes in Computer Science*Vol. 6795, (*Proceedings of the 15th International Conference on Developments in Language Theory*), 2011, pp. 417-428. - A. C. Cem Say, Abuzer Yakaryılmaz, "Finite state
verifiers with constant randomness,"
*Lecture Notes in Computer Science*Vol. 7318,*How the World Computes: Turing Centenary Conference and 8th Conference on Computability in Europe*,*CiE 2012*, Cambridge, UK, June 18-23, 2012,*Proceedings*, 2012, pp.646-654. - Uğur Küçük, A. C. Cem Say, Abuzer Yakaryılmaz, "Finite automata with advice tapes," LNCS Vol. 7907, (Proceedings of the 17th International Conference on Developments in Language Theory) pp. 301-312, 2013.
- Özlem Salehi, Abuzer Yakaryılmaz, A. C. Cem Say, "Real-time vector automata," LNCS Vol. 8070, (Proceedings of the 19th International Symposium on Fundamentals of Computation Theory) pp. 293-304, 2013.
- Abuzer Yakaryılmaz, A. C. Cem Say, Gökalp Demirci, "Debates with small transparent quantum verifiers," LNCS Vol. 8633, (Proceedings of the 18th International Conference on Developments in Language Theory) pp. 327-338, 2014.
- Ryan O’Donnell, A. C. Cem Say, "One time-traveling bit is as good as logarithmically many," LIPIcs Vol. 29 (Proceedings of the 34th International Conference on Foundation of Software Technology and Theoretical Computer Science) pp. 469-480, 2014. http://eccc.hpi-web.de/report/2014/091
- Cafer Caferov, Barış Kaya, Ryan O’Donnell, A. C. Cem Say, "Optimal bounds for estimating entropy with PMF queries," LNCS Vol. 9235, (Proceedings of the 40th International Symposium on Mathematical Foundations of Computer Science) pp. 187-198, 2015.
- Özlem Salehi, Flavio D’Alessandro, A. C. Cem Say, “Generalized results on monoids as memory,” E. Csuhaj-Varjú, P. Dömösi, Gy. Vaszil (Eds.): 15th International Conference on Automata and Formal Languages (AFL 2017) EPTCS 252, 2017, pp. 234–247, doi:10.4204/EPTCS.252.22

- Reha
Kamil Gerçeker, A. C. Cem Say, "Using polynomial approximations to
discover qualitative models," Proceedings of the
*20*Editors: Chris Bailey-Kellogg and Benjamin Kuipers, pp. 71-80, Darthmouth College, Hanover, New Hampshire, USA, 2006.^{th}International Workshop on Qualitative Reasoning. - Nuri Taşdemir, A. C. Cem Say,
"Provably spurious qualitative simulation predictions that just won’t
go away," Proceedings of the
*21*Editor: Chris Price, pp. 170-180, Aberystwyth, UK, 2007.^{st}International Workshop on Qualitative Reasoning. - Abuzer
Yakaryılmaz, A. C. Cem Say, "Language
recognition by generalized quantum finite automata with unbounded error,"
*4*, TQC2009, Waterloo, Ontario, Canada, 2009. (arXiv:0901.2703).^{th}Workshop on Theory of Quantum Computation, Communication, and Cryptography - Abuzer
Yakaryılmaz, A. C. Cem Say, "NP has log-space verifiers with fixed-size public
quantum registers," (
*8th Central European Quantum Information Processing Workshop*), 2011. [arXiv:1101.5227] - Gökalp Demirci, Mika
Hirvensalo, Klaus
Reinhardt, A. C. Cem Say, Abuzer Yakaryılmaz, "Classical and quantum realtime alternating
automata," 6th International Workshop on Non-Classical Models of
Automata and Applications, 2014. (arXiv: 1407.0334)
- A. C. Cem Say, Abuzer Yakaryılmaz, "Magic
coins are useful for small-space quantum machines," http://eccc.hpi-web.de/report/2014/159/
- Özlem
Salehi, A. C. Cem Say, "Homing vector automata," 7th
International Workshop on Non-Classical Models of Automata and
Applications, 2015. (arXiv:1504.04859)
- Uğur Küçük, A. C. Cem Say, Abuzer Yakaryılmaz,
"Inkdots as advice to small-space machines," arXiv:1509.03712.
- Özlem
Salehi, Ahmet Celal Cem Say, “Extended finite automata and decision
problems for matrix semigroups”, Tenth Workshop on Non-Classical Models of
Automata and Applications, NCMA 2018 (21.08-22.08)

- M. Ufuk Çağlayan, Fedon Kadifeli, A. C. Cem Say.
*Standard C Programming*. Boğaziçi University Publications, 1989. - Fedon Kadifeli, A. C. Cem Say, M. Ufuk
Çağlayan.
*Standart C Programlama Dili*(in Turkish). Sarmal Yayınları, 1993. (Translated and updated from (1) by F. Kadifeli.) - Cem Say,
*50 Soruda Yapay Zekâ*. Bilim ve Gelecek Kitaplığı, 2018

- Selahattin Kuru, H. Levent Akın, A. C. Cem
Say, Ethem Alpaydın
(Eds.).
*İkinci Türk Yapay Zeka ve Yapay Sinir Ağları Sempozyumu Bildiriler*. Boğaziçi Üniversitesi, İstanbul, 1993. - A. C. Cem Say, Günhan Dündar (Eds.)
*Proceedings of the Eighth Turkish Symposium on Artificial Intelligence and Neural Networks.*Boğaziçi Üniversitesi, İstanbul, 1999.

- A. C. Cem Say, "Sen de mi şair oldun ey
bilgisayar?"
*Çağrı Dergisi*, no. 400, 1993, p. 9. - A. C. Cem Say, "Sıcak bir TAINN
günü"
*Beşinci Türk Yapay Zeka ve Yapay Sinir Ağları Sempozyumu*, İstanbul, 1996, p. 381. - Cem Say, "Akla doğru"
*Cogito*, no. 13, 1998, pp. 67-74. - Cem Say, "Gödel’in eksiklik teoremi"
*Matematik Dünyası*, Yıl 14, Sayı 4, 2005, 67-71. - Cem Say, "Nitel benzetim"
*Türkiye Bilişim Ansiklopedisi*. TBV-Papatya Yayıncılık Eğitim, 611-615, 2006. - Cem Say, "Yapay zeka, doğal zeka ve
özgürlük"
*Bilim ve Ütopya*, Yıl 18, Sayı 220, 2012, 42-48. - A. C. Cem Say, "Diller, çözümsüz
problemler ve sonsuzluk"
*Bilgisayar ve Beyin: "Bilgi İşleyen Makine Olarak Beyin" Toplantıları*, yayına hazırlayan: Haluk Bingöl, Pan Yayıncılık, 177-184, 2012. - Cem Say, "Yapay zeka ve Gödel
teoremi"
*Bilgisayar ve Beyin: "Bilgi İşleyen Makine Olarak Beyin" Toplantıları*, yayına hazırlayan: Haluk Bingöl, Pan Yayıncılık, 254-264, 2012. - A.
C. Cem Say, Abuzer Yakaryılmaz, "Quantum finite
automata: A modern introduction,"
*Computing with New Resources,*LNCS Vol. 8808, (Essays Dedicated to Josef Gruska on the Occasion of His 80th Birthday) pp. 208-222, 2014. arXiv: 1406:4048

**Doctoral Dissertation**:
Qualitative System Identification. Boğaziçi University,
1992. (First thesis of Boğaziçi’s Computer Engineering PhD program)