59th ISFE	Kościelisko, June 15, 2024	Kazuki Okamura, Péter Tóth
59th ISFE	Hajdúszoboszló, June 24, 2023	Mehak Iqbal, Amr Zakaria
58th ISFE	Innsbruck, June 26, 2022	Paweł Pasteczka
57th ISFE	Jastarnia, June 8, 2019	Tibor Kiss, Andrzej Olbryś
56th ISFE	Graz, June 23, 2018	Paolo Leonetti, Imke Toborg
55th ISFE	Chengdu, June 17, 2017	Liu Liu, Wenmeng Zhang
54th ISFE	Hajdúszoboszló, June 19, 2016	Radosław Łukasik, Patrícia Szokol
53rd ISFE	Krynica-Zdrój, June 20, 2015	Gergely Kiss, Jolanta Olko
52nd ISFE	Innsbruck, June 28, 2014	Eliza Jabłońska, Adrienn Varga
51st ISFE	Rzeszów, June 22, 2013	Wojciech Jabłoński, Judit Makó
50th ISFE	Hajdúszoboszló, June 23, 2012	Włodzimierz Fechner, Gergő Nagy
49th ISFE	Graz, June 25, 2011	Jörg Tomaschek, Barbara Przebieracz
48th ISFE	Batz-sur-Mer, June 18, 2010	Eszter Gselmann, Justyna Jarczyk
47th ISFE	Gargnano, June 20, 2009	Marta Štefánková, Szymon Wąsowicz
46th ISFE	Opava, June 28, 2008	Attila Házy, Tomasz Kochanek
45th ISFE	Bielsko-Biała, June 30, 2007	Jacek Chmieliński, Jacek Chudziak
44th ISFE	Louisville, May 19, 2006	Janusz Morawiec, Dilian Yang
43rd ISFE	Batz-sur-Mer, May 20, 2005	Roman Badora
42nd ISFE	Hradec nad Moravicí, June 26, 2004	Ekaterina Shulman, Justyna Sikorska
41st ISFE	Noszvaj, June 14, 2003	Mihály Bessenyei, Harald Fripertinger
40th ISFE	Gronów, August 31, 2002	Janusz Brzdęk, Tomasz Szostok
39th ISFE	Sandbjerg Estate, August 17, 2001	Attila Gilányi
38th ISFE	Noszvaj, June 17, 2000	Zoltán Boros
37th ISFE	Huntington, May 22, 1999	Nicole Brillouët-Belluot
36th ISFE	Brno, May 29, 1998	Lajos Molnár, Maciej Sablik
35th ISFE	Graz, September 13, 1997	Roland Girgensohn
34th ISFE	Wisła Jawornik, June 19, 1996	Zsolt Páles, Jacek Tabor
33rd ISFE	Caldes de Malavella, May 27, 1995	Wolfgang Förg-Rob, György Szabó
32nd ISFE	Gargnano, June 18, 1994	Antal Járai, Peter Šemrl
31st ISFE	Debrecen, August 28, 1993	Witold Jarczyk
30th ISFE	Oberwolfach, September 26, 1992	Gyula Maksa

The meetings on functional equations, which are now called International Symposium on Functional Equations, have been held annually since 1962 (with the exception of 1964, 2020 and 2021). The first conference, with 14 participants from 5 countries, was organized by Professors J. Aczél, O. Haupt and A. Ostrowski in the Mathematical Research Institute of Oberwolfach, Germany. Of the previous 60 symposia, 15 took place in Germany, 9 in Poland, 7 in Austria, 6 in Hungary, 5 in each of Canada and Italy, 3 in each of the Czech Republic, France and the United States, 2 in Spain, and 1 in each of China, Denmark and Switzerland.

Nowadays, the series has an international scientific committee which invites leading specialists in the field to attend a symposium. The average number of participants of the last five meetings is about 65, and they came from Austria, Brazil, Canada, China, the Czech Republic, Denmark, Egypt, France, Germany, Hungary, Iran, Israel, Italy, Japan, Luxembourg, Poland, Portugal, Republic of Korea, Romania, Russia, Saudi Arabia, Spain, South Africa, Switzerland, the United States and Venezuela. The reports of meetings are published in Aequationes Mathematicae.

Every participant has an opportunity to give a 20-minute long talk. As usual, besides regular talks, there will also be a longer survey lecture. Furthermore, a special session and several sessions devoted to problems and remarks will be organized. 

Gian Luigi Forti - University of Milan, Italy
Roman Ger - Silesian University, Poland
Zsolt Páles - University of Debrecen, Hungary
Maciej Sablik (chairman) - Silesian University, Poland
Jens Schwaiger - University of Graz, Austria
Ekaterina Shulman - Silesian University, Poland
László Székelyhidi - University of Debrecen, Hungary

honorary members:
János Aczél (honorary chairman) - University of Waterloo, Canada
Zoltán Daróczy - University of Debrecen, Hungary
Jürg Rätz- University of Bern, Switzerland
Ludwig Reich - University of Graz, Austria

ACZÉL, János December 26th, 1924 - January 1st, 2020

picture source: https://unideb.hu/hu/node/1282

János Aczél, UWaterloo professor emeritus of mathematics, died peacefully following a brief illness. He had celebrated his 95th birthday only six days prior. Born in Budapest, Hungary, János spent his early years earning a doctorate in mathematical analysis from the University of Budapest and holding positions at the University of Cologne, Kossuth University, University of Miskolc, and University of Szeged before moving to Canada with his family in 1965 at which time he joined the faculty at the University of Waterloo, becoming a Distinguished Professor Emeritus in the Department of Pure Mathematics. Throughout his successful career he was the founder of the journal Aequationes Mathematicae, first published in 1968, and remains its honorary editor-in-chief, held honorary degrees from the University of Karlsruhe, the University of Graz, and the University of Silesia in Katowice. In 1971, he was elected a fellow of the Royal Society of Canada. In 1990 he became an external member of the Hungarian Academy of Sciences and in 2008 he became an honorary member of the Hamburg Mathematical Society, the oldest active mathematical society in the world. He was the 1988 winner of the Santiago Ramón y Cajal Medal and in 2004 he won the Kampé de Fériet Award of the annual Information Processing and Management of Uncertainty conference, "for his pioneering work on the theory of functional equations, with applications in many fields, such as information measures, index numbers, group decision making, aggregation, production functions, laws of science, theory of measurement and utility theory." Issues of the journal Aequationes Mathematicae were dedicated to Aczél in 1999, 2005, and 2010, in honor of his 75th, 80th, and 85th birthdays. Aczél authored and co-authored: Aczél, J.; Gołąb, S. (1960), Funktionalgleichungen der Theorie der geometrischen Objekte, Polska Akademia Nauk. Monografie Matematyczne; Aczél, J. (1966), Lectures on functional equations and their applications, mathematics in Science and Engineering - Previously published in German as Vorlesungen über Funktionalgleichungen und ihre Anwendungen (Birkhäuser, 1961); Aczél, J.; Daróczy, Z. (1975), On measures of information and their characterizations, Mathematics in Science and Engineering; Aczél, J. (1987), A short course on functional equations, Theory and Decision Library. Series B: Mathematical and Statistical Methods, Dordrecht; Aczél, J.; Dhombres, J. (1989), Functional equations in several variables, Encyclopedia of Mathematics and its Applications. He was also the founder and Honorary Chairman of the series of International Symposia on Functional Equations. We will always treasure our memories of his life and recall his gentle, caring attitude and wisdom. His passion for mathematics will continue through the talented graduate students who continue to push forward the boundaries of mathematics and pure reason. Their future discoveries will result in far-reaching benefits for Canada at home and abroad. To this end, the Aczél family have established the János and Susan Aczél Graduate Scholarship at the University of Waterloo. The above text is based on Obituary Overview. Celebration of Life Ebanks, B., Ng, C.T. "In celebration of the life of Professor János Aczél." Aequat. Math. 94, 401–404 (2020). János Aczél Obituary Sharing Memories

60th ISFE - June 9 - 15, 2024, Kościelisko, Poland - see the webpage

59th ISFE - June 18 - 25, 2023, Hajdúszoboszló, Hungary - see the webpage

58th ISFE - June 19 - 26, 2022, Innsbruck, Austria - see the webpage

57th ISFE - June 2 - 9, 2019, Jastarnia, Poland - see the webpage

56th ISFE - June 17 - 24, 2018, Graz, Austria - see the webpage

55th ISFE - June 11 - 18, 2017, Chengdu, China - see the webpage

54th ISFE - June 12 - 19, 2016, Hajdúszoboszló, Hungary - see the webpage

53rd ISFE - June 14 - 21, 2015, Krynica-Zdrój, Poland - see the webpage

52nd ISFE - June 22 - 29, 2014, Innsbruck, Austria

51st ISFE - June 16 - 23, 2013, Rzeszów, Poland

50th ISFE - June 17 - 24 , 2012, Hajdúszoboszló, Hungary

49th ISFE - June 19 - 26, 2011, Graz, Austria

48th ISFE - June, 13 - 18, 2010, Batz-sur-Mer, France

47th ISFE - June 14 - 21, 2009, Gargnano, Italy

46th ISFE - June 22 - 29, 2008, Opava, Czech Republic

45th ISFE - June 24 - July 1, 2007, Bielsko-Biała, Poland

44th ISFE - May 14 - 20, 2006, Louisville, Kentucky, USA

43rd ISFE - May 15 - 21, 2005, Batz-sur-Mer, France

42nd ISFE - June 20 - 27, 2004, Opava, Czech Republic - see the webpage

41st ISFE - June 8 - 15, 2003, Noszvaj, Hungary

40th ISFE - August 25 - September 1, 2002, Gronów, Poland

39th ISFE - August 12 - 18, 2001, Sandbjerg, Denmark

38th ISFE - June 11 - 18, 2000, Noszvaj, Hungary

37th ISFE - May 16 - 23, 1999, Huntington, West Virginia, USA - see the webpage

36th ISFE - May 24 - 30, 1998, Brno, Czech Republic

35th ISFE - September 7 - 14, 1997 Graz, Austria

34th ISFE - June 10 - 19, 1996, Wisła-Jawornik, Poland

33rd ISFE - May 21 – 27, 1995, Caldes de Malavella, Catalonia, Spain

32nd ISFE - June 12 – 19, 1994, Gargnano, Italy

31st ISFE - August 22 - 28, 1993, Debrecen, Hungary

30th ISFE - September 20 – 26, 1992, Oberwolfach, Germany

29th ISFE - June 3 - 10, 1991, Wolfville, N.S., Canada

28th ISFE - August 23 – September 1, 1990, Graz-Mariatrost, Austria

27th ISFE - August 14 – 24, 1989, Bielsko-Biała - Katowice - Kraków, Poland

26th ISFE - April 24 - May 3, 1988, Sant Feliu de Guixols, Catalonia, Spain

25th ISFE - August 16 - 22, 1987, Hamburg-Rissen, Germany

24th ISFE - August 12 - 20, 1986, South Hadley, MA, USA

23rd ISFE - June 2 - 11, 1985, Gargnano, Italy

22nd ISFE - December 16 – 22, 1984, Oberwolfach, Germany

21st ISFE - August 6 - 13, 1983, Konolfingen, Switzerland

20th ISFE - August 1 – 7, 1982, Oberwolfach, Germany

19th ISFE - May 3 – 13, 1981, Nantes and La Turballe, France

18th ISFE - August 26 - September 6, 1980, Waterloo and Scarborough, Ontario, Canada

17th ISFE - May 17 - 23, 1979, Oberwolfach, Germany

16th ISFE - September 3 - 10, 1978, Leibnitz, Austria

15th ISFE - May 22 – 28, 1977, Oberwolfach, Germany

14th ISFE - May 21-28, 1976, Lecce and Castro Marina, Italy

13th ISFE - July 6 - 12, 1975, Oberwolfach, Germany

12th ISFE - August 30 - September 9, 1974, Victoria Harbour, Ontario, Canada

11th ISFE - December 14 - 20, 1973, Oberwolfach, Germany

10th ISFE - July 30 - August 5, 1972, Oberwolfach, Germany

9th ISFE - September 3 – 11, 1971, Rome and Procchio (Isle of Elba), Italy

8th ISFE - August 2 - 8, 1970, Oberwolfach, Germany

7th ISFE - September 1 – 13, 1969, Waterloo, Ontario, Canada

6th ISFE - June 17 - 22, 1968, Oberwolfach, Germany

5th ISFE - April 24 - 29, 1967, Waterloo, Ontario, Canada

4th ISFE - June 10 - 16, 1966, Oberwolfach, Germany

3rd ISFE - July 5 - 10, 1965, Oberwolfach, Germany

2nd ISFE - October 7 - 11, 1963, Oberwolfach, Germany

1st ISFE - September 2 - 8, 1962, Oberwolfach, Germany

The 61st ISFE is planned for June 2025 in Cluj-Napoca, Romania.

More details can be found at the webpage of the 61st ISFE.

59th ISFE - Aequationes mathematicae, Volume 97, Issue 5-6, pp 1259 - 1290

58th ISFE - Aequationes mathematicae, Volume 96, Issue 6, pp 1365 - 1385

57th ISFE - Aequationes mathematicae, Volume 93, Issue 6, pp 1325–1349

56th ISFE - Aequationes mathematicae, Volume 93, Issue 6, pp 1293–1324

55th ISFE - Aequationes mathematicae, Volume 92, Issue 6, pp 1167–1193

54th ISFE - Aequationes mathematicae, Volume 91, Issue 6, pp 1157–1204

53rd ISFE - Aequationes mathematicae, Volume 90, Issue 6, pp 1241–1269

52nd ISFE - Aequationes mathematicae, Volume 89, Issue 6, pp 1509–1551

51st ISFE - Aequationes mathematicae, Volume 88, Issue 3, pp 291–320

50th ISFE - Aequationes mathematicae, Volume 86, Issue 3, pp 289–320

49th ISFE - Aequationes mathematicae, Volume 84, Issue 3, pp 285–318

48th ISFE - Aequationes mathematicae, Volume 81, Issue 3, pp 285–318

47th ISFE - Aequationes mathematicae, Volume 79, Issue 1–2, pp 173–202

46th ISFE - Aequationes mathematicae, Volume 77, Issue 3, pp 303–327

45th ISFE - Aequationes mathematicae, Volume 75, Issue 1–2, pp 163–200

44th ISFE - Aequationes mathematicae, Volume 73, Issue 1–2, pp 172–200

43rd ISFE - Aequationes mathematicae, Volume 71, Issue 1–2, pp 174–200

42nd ISFE - Aequationes mathematicae, Volume 69, Issue 1–2, pp 164–200

41st ISFE - Aequationes mathematicae, Volume 67, Issue 3, pp 285–320

40th ISFE - Aequationes mathematicae, Volume 65, Issue 3, pp 288–320

39th ISFE - Aequationes mathematicae, Volume 64, Issue 1–2, pp 170–200

38th ISFE - Aequationes mathematicae, Volume 61, Issue 4, pp 281–320

37th ISFE - Aequationes mathematicae, Volume 60, Issue 1-2, pp 175–200

36th ISFE - Aequationes mathematicae, Volume 56, Issue 3, pp 284–318

35th ISFE - Aequationes mathematicae, Volume 55, Issue 3, pp 281–318

34th ISFE - Aequationes mathematicae, Volume 53, Issue 1–2, pp 162–205

33rd ISFE - Aequationes mathematicae, Volume 51, Issue 1–2, pp 145–180

32nd ISFE - Aequationes mathematicae, Volume 49, Issue 1, pp 166–202

31st ISFE - Aequationes mathematicae, Volume 47, Issue 2–3, pp 263–327

30th ISFE - Aequationes mathematicae, Volume 46, Issue 3, pp 264–307

29th ISFE - Aequationes mathematicae, Volume 43, Issue 2-3, pp 264–309

28th ISFE - Aequationes mathematicae, Volume 41, Issue 1, pp 248–312

27th ISFE - Aequationes mathematicae, Volume 39, Issue 2–3, pp 264–329

26th ISFE - Aequationes mathematicae, Volume 37, Issue 1, pp 57–127

25th ISFE - Aequationes mathematicae, Volume 35, Issue 1, pp 82–124

24th ISFE - Aequationes mathematicae, Volume 32, Issue 1, pp 96–150

23rd ISFE - Aequationes mathematicae, Volume 30, Issue 1, pp 284–287

22nd ISFE - Aequationes mathematicae, Volume 29, Issue 1, pp 62–111

21st ISFE - Aequationes mathematicae, Volume 26, Issue 1, pp 225–294

20th ISFE - Aequationes mathematicae, Volume 24, Issue 1, pp 261–297

19th ISFE - Aequationes mathematicae, Volume 23, Issue 1, pp 118–121

18th ISFE - Aequationes mathematicae, Volume 22, Issue 1, pp 108–111

17th ISFE - Aequationes mathematicae, Volume 20, Issue 1, pp 286–315

16th ISFE - Aequationes mathematicae, Volume 19, Issue 1, pp 245–299

15th ISFE - Aequationes mathematicae, Volume 17, Issue 1, pp 348–378

14th ISFE - Aequationes mathematicae, Volume 15, Issue 2–3, pp 265–300

13th ISFE - Aequationes mathematicae, Volume 14, Issue 1–2, pp 197–236

12th ISFE - Aequationes mathematicae, Volume 12, Issue 2–3, pp 262–310

11th ISFE - Aequationes mathematicae, Volume 11, Issue 2–3, pp 277–314

10th ISFE - Aequationes mathematicae, Volume 10, Issue 2–3, pp 286–310

9th ISFE - Aequationes mathematicae, Volume 8, Issue 1–2, pp 136–189

8th ISFE - Aequationes mathematicae, Volume 6, Issue 1, pp 90–111

7th ISFE - Aequationes mathematicae, Volume 4, Issue 1–2, pp 205–257

6th ISFE - Aequationes mathematicae, Volume 2, Issue 2–3, pp 348–376

5th ISFE - Aequationes mathematicae, Volume 1, Issue 3, pp 275–305

4th ISFE - Aequationes mathematicae, Volume 1, Issue 1–2, pp 135–149

3rd ISFE - Aequationes mathematicae, Volume 1, Issue 1–2, pp 122–134

2nd ISFE - Mathematisches Forschungsinstitut Oberwolfach, Workshop Report 1963,16, pp 1–15

1st ISFE - Mathematisches Forschungsinstitut Oberwolfach, Workshop Report 1962,10, pp 1–12

60th ISFE	chair: T. Rajba, T. Szostok	Stochastic orders and their relations to functional equations and inequalities
59th ISFE	chair: J. Chudziak	The role of functional equations in decision making
58th ISFE	chair: J. Chmieliński	Various aspects of functional equations and inequalities occurring in functional analysis
57th ISFE	chair: T. Szostok	Probabilistic methods in functional equations
56th ISFE	chair: P. Burai	Schur convexity
55th ISFE	chair: E. Shulman	Polynomial functions and exponential polynomials
54th ISFE	chair: K. Nikodem	Multifunctions in the theory of functional equations
53rd ISFE	chair: J.-L. Marichal	Associativity, generalizations and applications
52nd ISFE	chair: M. Sablik	Alienation of functional equations
50th ISFE	chair: W. Fechner	Inequalities
49th ISFE	chair: Ja. Tabor	Convexivity
48th ISFE	chair: Z. Daróczy, J. Matkowski	Means and related functional equations and inequalities
46th ISFE	chair: W. Jarczyk, K. Lajkó	Functional equations stemming from probability theory
45th ISFE	chair: G. Maksa, M. Bessenyei	Convexity
44th ISFE	chair: R. Badora, G.-L. Forti	New results on stability
43rd ISFE	chair: A. Járai, Zs. Páles	Implications among regularity conditions on solutions of functional equations and functional inequalities
42nd ISFE	chair: J. Smital	Dynamical systems
41st ISFE	chair: W. Jarczyk	Linear iterative equations
40th ISFE	chair: Z. Daróczy	Mean values
38th ISFE	chair: B. Ebanks	Recent developments on the cocycle equation
37th ISFE	chair: D. Gronau	History of functional equations
35th ISFE	chair: R.D. Luce	Applications of functional equations to the theory of measurement and in the behavioral sciences
	chair: K. Baron, W. Förg-Rob	Schilling's problem
34th ISFE	chair: J. Aczél	Selection models
	chair: R. Ger, Jó. Tabor	Hyers-Ulam stability
33rd ISFE		Life and work of Karl Menger on the 10th anniversary of his death
32nd ISFE		Many aspects and applications of bisymmetry
29th ISFE		Algebraic aspects of functional equations theory
		A problem on generalized plurality functions in the social sciences
28th ISFE		Functional equations and geometry
		New results in stability theory
		The translation equation and iteration theory
		Functional equations in power series rings
27th ISFE	chair: C. Alsina	Functional equations in the teaching of mathematics
	chair: J. Matkowski, J. Rätz	Functional equations and functional inequalities in functional analysis
	chair: J. Aczél, F. Stehling	Some applications of functional equations outside mathematics
26th ISFE	chair: R. Ger	Stability
	chair: W. Eichhorn, W. Gehrig	Applications to social sciences
	chair: B. Schweizer, A. Sklar	Probabilistic metric spaces and related topics
	chair: Z. Moszner, L. Reich, Gy. Targonski	Iteration theory
25th ISFE	chair: C. Alsina, W.Eichhorn	Applications of functional equations to architecture and economics
24th ISFE	chair: L. Reich, A. Sklar, Gy. Targonski	Iteration theory
	chair: J. Rätz	Orthogonal additivity
	chair: C. Alsina	Probabilistic metrics and related topics
23rd ISFE		Iteration theory
		Information measures
		Functional transforms
21st ISFE	chair: D. Gronau,L. Reich	Iteration theory
	chair: J.B. Miller	Functional equations in functional analysis
20th ISFE	chair: F. Radó	Characterization theorems in geometric algebra
	chair: Z. Moszner	Theory of the translation equation and on iteration theory
	chair: G. Maksa	Information Measures
19th ISFE		Iteration theory
		functional equations on n-ary groupoids
		Information Measures
18th ISFE		Iteration theory
		Information Measures

Participation in these annual meetings is by invitation only. Those wishing to attend the ISFE meetings should send information on their scientific interest and, preferably, publications together with their postal and email addresses to

Maciej Sablik
Chairman of the Scientific Committee

Institute of Mathematics
Silesian University
Bankowa 14
40-007 Katowice
Poland
email: maciej.sablik@us.edu.pl

60th ISFE	Mihály Bessenyei	Geometrical methods in separation problems
59th ISFE	J. Schwaiger	Remarks on inhomogeneous functional equations
58th ISFE	Zs. Páles	Associativity, bisymmetry and distributivity - a tribute to János Aczél
	L. Székelyhidi	János Aczél in his own work
57th ISFE	E. Gselmann	Polynomial solutions of functional equations - methods with and without spectral theory
56th ISFE	K. Nikodem	Strongly convex functions
55th ISFE	L. Székelyhidi	Spectral analysis and spectral synthesis
54th ISFE	R. Badora	Stability and functional analysis
53rd ISFE	J. Morawiec	Wavelets and functional equations
52nd ISFE	W. Jarczyk	Convexity on groups
51st ISFE	J. Sikorska	Orthogonalities and functional equations
50th ISFE	J. Schwaiger	Generalized polynomials
49th ISFE	G. Maksa	Derivations
48th ISFE	L. Székelyhidi	Spectral synthesis and spectral analysis
47th ISFE	J. Smítal	Dynamical systems and functional equations
45th ISFE	M.C. Zdun	Functional equations in iteration theory – recent results
44th ISFE	L. Reich	Recent results on functional equations in power series rings
43rd ISFE	J. Dhombres	Functional equations in the eighteenth century
	R. Ger	Functional equations related to functional analysis
42nd ISFE	H. Stetkær	Functional equations on groups - recent results
41st ISFE	J. Brzdęk	The Gołąb–Schinzel equation and its generalizations
40th ISFE	K. Baron	Recent results in the theory of functional equations in a single variable
38th ISFE	R.Girgensohn	Schilling's equation and related problems
37th ISFE	M. Sablik	On a functional equation of Abel
36th ISFE	Zs. Páles	Functional inequalities and their applications
35th ISFE	W. Benz	Recent results on functional equations in geometry
34th ISFE	K. Nikodem	Functional equations involving set-valued functions
33rd ISFE	L. Reich	Functional equations for formal power series
32nd ISFE	H.-H. Kairies	Functional equations for special and peculiar functions
30th ISFE	J. Aczél	Some recent applications of functional equations to the social and behavioral sciences. Further problems
	K. Baron	Recent results on functional equations in a single variable, perspectives and open problems
	W. Benz	Invariants and mappings. Functional equations in geometry.
	G.-L. Forti	Stability of functional equations
	A. Járai, L. Székelyhidi	General methods and regularization in the theory of functional equations
	Z. Moszner, G. Targonski	General theory of the translation equation and a survey of recent results and problems in iteration theory
	L. Paganoni, J. Rätz	Conditional functional equations and orthogonal additivity