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

- Introduction
to ACCS
- Personal
Details
- 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.

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*, Vol. 12, 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.

- 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, RūsiņÅ¡ 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/
- Ryan O’Donnell, A. C. Cem Say, "The weakness of CTC qubits and the power of
approximate counting," 2015.
- 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, Flavio D’Alessandro and
A. C. Cem Say, “Language classes associated with automata over matrix
groups” In Proceedings of the Eighth Workshop on Non-Classical Models of
Automata and Applications, NCMA’16, pages 287-300. 2016.

- 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.)

- 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)