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Alexander Kechris

Professor of Mathematics, Emeritus
Contact information for Alexander Kechris
Contact Method Value
Mail Code: MC 253-37
Office: 379 Linde Hall (37)
Phone: 626-395-4368
M.S., National Technical University, Athens, 1969; Ph.D., University of California, Los Angeles, 1972; D.h.c., University of Athens. Assistant Professor, Caltech, 1974-76; Associate Professor, 1976-81; Professor, 1981-25; Professor, Emeritus, 2025-. Executive Officer for Mathematics, 1994-97.
Research Areas: Mathematics
CV icon Curriculum vitae

Publications

Alekos' main research interests are in mathematical logic and its interaction with other areas of mathematics. He has made extensive contributions to the definability theory of the continuum and its  connections and applications to classical and harmonic analysis, ergodic theory, topological dynamics, combinatorics, computability theory and model theory.

Selected Publications

  • Definable cardinality, preprint, 2025. Click here for the .pdf file
  • (with T. Arant and P. Lutz) Borel graphable equivalence relations, preprint, 2024. Click here for the arXiv
  • (with M. Wolman) Invariant uniformization, preprint 2024. Click here for the arXiv
  • The spaces of measure preserving equivalence relations and graphs, preprint 2024. Click here for the .pdf file
  • (with M. Wolman) Ditzen's effective version of Nadkarni's Theorem, preprint 2024. Click here for the .pdf file.
  • (with J. Frisch,  F. Shinko and Z. Vidnyánszky) Realizations of countable Borel equivalence relations, preprint, 2023. Click here for the arXiv
  • The theory of countable Borel equivalence relations. This material has been published by Cambridge University Press as "The theory of countable Borel equivalence relations" by Alexander S. Kechris. This pre-publication version is free to view and download for personal use only. Not for re-distribution, re-sale or use in derivative works. ©  Alexander S. Kechris 2024.Click here for the .pdf file
  • (with J. Frisch and F. Shinko) Lifts of Borel actions on quotient spaces, Israel J. Math., special volume for Benjamin Weiss, 251 (2022), 379-421. Click here for the Sharedit
  • (with M. Malicki, A. Panagiotopoulos and J. Zielinski) On Polish groups admitting non-essentially countable actions, Erg. Theory and Dynam. Systems, 42 (2022), 180--194. Click here for the . pdf file
  • Global aspects of measure preserving equivalence relations and graphs, New Zealand Journal of Math., Vaughan Jones Memorial Issue, 52 (2021), 691-726. Click here for the .pdf file
  • (Co-edited with N. Makarov, D. Ramakrishnan and X. Zhu) Nine Mathematical Challenges: An Elucidation, Proc. of Symp. in Pure Math., 104, American Mathematical Society, 2021.
  • (Co-edited with B. Loewe and J.R. Steel) ,  Large cardinals, determinacy and other topics, Lecture Notes in Logic 49, Cambridge University Press, 2021.
  • Quasi-invariant measures for continuous group actions, Trends in Set Theory, Ed. by S. Coskey and G. Sargsyan, Contemp. Math., 752 (2020), 113-120. Click here for the . pdf file  
  • (with P.J. Burton) Weak containment of measure preserving group actions, Erg. Theory and Dynam. Systems, 40, (2020), 2681--2733. Click here for the . pdf
  • (with A.S. Marks) Descriptive graph combinatorics, preprint, 2020. Click here for the . pdf file
  • (with V. Quorning) Co-induction and invariant random subgroups, Groups, Geometry, and Dynamics, 13(4) (2019), 1151--1193. Click here for the arXiv
  • (with R. Chen) Structurable equivalence relations, Fund. Math., 242 (2018), 109--185. Click here for the . pdf file. arXiv expanded version  arXiv
  • (with A. Nies and K. Tent) The complexity of topological group isomorphism,J. Symb. Logic, 83(3) (2018), 1190--1203. Click here for the . pdf file
  • (with P.J. Burton ) Invariant random subgroups and action versus represe ntation maximality, Proc. Amer. Math. Soc., 145(9) (2017), 3961--3971. Click here for arXiv
  • (with M. Sokic and S. Todorcevic) Ramsey properties of finite measure algebras and topological dynamics of the group of measure preserving automorphisms: some results and an open problem, in: Foundations of Mathematics,  Essays in Honor of W. Hugh Woodin's 60th Birthday, Ed. by A.E. Caicedo et al., Contemp. Math., 690 (2017), 69-85,  Click here for the . pdf file
  • (Co-edited with B. Loewe and J.R. Steel) ,  Ordinal Definability and Recursion Theory: The Cabal Seminar, Volume III, Lecture Notes in Logic 43, Cambridge University Press, 2016.
  • (with D.A. Martin) On the theory of $\Pi^1_3$ sets of reals, II , in:  Ordinal Definability and Recursion Theory:  The Cabal Seminar, Volume III, Lecture Notes in Logic 43, Cambridge University Press, 2016, 200-219.
  • (with H.L. Macdonald) Borel equivalence relations and cardinal algebras, Fund. Math., 235 (2016), 183--198. Click here for the .pdf file
    • Corrections: . pdf
  • Commentary on Problem 50 (of Banach) in the Scottish Book, in: R. D. Mauldin, The Scottish Book, Second Edition, Birkhäuser, 2015, 127-129. Click here for the . pdf file
  • (with O. Angel and R. Lyons) Random orderings and unique ergodicity of automorphism g roups, J. European Math. Society, 16 (2014), 2059-2095. Click here for the  . pdf file
  • Dynamics of non-archimedean Polish groups, European Congress of Mathematics, Krakow, 2-7 July, 2012, 375-397, R. Latala et al., Eds., European Math. Society, 2014.
  • (with C. T. Conley and R.D. Tucker-Drob) Ultraproducts of measure preserving actions and graph combinatorics, Erg. Theory and Dynam. Systems, 33 (2013), 334-373.
  • (with C.T. Conley) Measurable chromatic and independence numbers for ergodic graphs and group actions,  Groups, Geometry, and Dynamics, 7 (2013), 127-180.
  • (with R.D. Tucker-Drob) The complexity of classification problems in ergodic theory, Appalachian Set Theory, Ed. by J. Cummings and E. Schimmerling, London Math. Society Lecture Note Series, 406, 265-299, Cambridge University Press, 2013.
  • (with C.T. Conley and B.D. Miller) Stationary probability measures and topological realizations, Israel. J. Math., 198 (1) (2013), 333-345.
  • Trigonometric series and set theory, Wiadomosci Matematyczne, 48(2) (2012), 109–118. Click here for the  . pdf file
  • (Co-edited with B. Loewe and J.R., Steel) , Wadge degrees and projective ordinals: The Cabal Seminar, Volume II ,  Lecture Notes in Logic 37, Cambridge University Press, 2012.
  • (with M. Sokic) Dynamical properties of the automorphism groups of the random poset and random distributive lattice, Fund. Math. 218 (2012), 69-94.
  • Weak containment in the space of actions of a free group, Israel J. Math. , 189 (2012), 461-507 .
  • In memoriam:  Gregory Hjorth (1963-2011), Bulletin of Symbolic Logic 17(3) (2011), 471-477.
                Corrections: pdf
  • Global aspects of ergodic group actions , Mathematical Surveys and Monographs, 160, American Mathematical Society, 2010. 
    • Corrections and Updates:   [ pdf].
  • (with A. Ioana and T. Tsankov) Subequivalence relations and positive-definite functions , Groups, Geometry, and Dynamics 3(4) (2009), 579-625.
  • Set theory and dynamical systems, Logic, Methodology and Philosophy of Science, Proc. of the Thirteenth International Congress, Ed. C. Glymour et al., College Publ., London, 2009, 97-107.
  • (Co-edited with B. Loewe and J.R. Steel) Games, Scales, and Suslin Cardinals:  The Cabal Seminar, Volume I, Lecture Notes in Logic 31, Cambridge University Press, 2008.
  • (with W.H. Woodin) The equivalence of partition properties and determinacy , in:  Games, Scales, and Suslin Cardinals:  The Cabal Seminar, Volume I, Lecture Notes in Logic 31, Cambridge University Press, 2008, 355-378.
  • (with W.H. Woodin) Generic codes for uncountable ordinals, partition proper ties, and elementary embeddings in:  Games, Scales, and Suslin Cardinals:  The Cabal Seminar, Volume I, Lecture Notes in Logic 31, Cambridge University Press, 2008, 379-397.
  • (with B.D. Miller) Means on equivalence relations, Israel. J. Math. 163 (2008), 241-262.
  • (with T. Tsankov) Amenable actions and almost invariant sets, Proc. Amer. Math. Soc. 136(2) (2008), 687-697.
  • (with C. Rosendal) Turbulence, amalgamation and generic automorphisms of homogeneous structures, Proceedings of the London Math. Society,  94(3) (2007), 302–350.
  • Unitary representations and modular actions, Journal of Math. Sciences, 140(3) (2007), 398-425.
  • (with G. Hjorth) Rigidity theorems for actions of product groups and countable Borel equivalence relations, Memoirs of the Amer. Math. Soc., 177, No. 833, 2005.
  • (with V.G. Pestov and S. Todorcevic) Fraïssé limits, Ramsey theory and topological dynamics of automorphism groups, Geometric and Functional Analysis 15 (1) (2005), 106-189.
  • (with B.D. Miller)  Topics in Orbit Equivalence, Lecture Notes in Mathematics, Springer, Vol. 1852, 2004
  • (with S. Gao) On the classification of Polish metric spaces up to isometry, Memoirs of Amer. Math. Soc., 766, Amer. Math. Soc., 2003.
  • (with C.W. Henson, J. Iovino and E. Odell) Analysis and Logic London Math. Soc. Lecture Notes Series, 262, Cambridge University Press, 2002. 
  • (with S. Jackson and A. Louveau) Countable Borel equivalence relations, J. Math. Logic 2(1) (2002), 1-80.
  • (with S.R. Buss, A. Pillay, and R.A. Shore The prospects for mathematical logic in the 21st century, Bull. Symb. Logic 7(2) (2001), 169-196.
  • (with J.D. Clemens and S. Gao) Polish metric spaces:  Their classification and isometry groups, Bull. Symb. Logic 7(3) (2001), 361-375.
  • (with G. Hjorth) Recent developments in the theory of Borel reducibility , Fund. Math. 170(1) (2001), 21-52 (volume dedicated to the memory of J. Los).
  • (with N. Sofronidis) A strong generic ergodicity property of unitary and self-adjoint operators, Ergodic Theory and Dynam. Systems 21 (2001), no. 5, 1459-1479.
  • (co-edited with  M. Foreman,  A. Louveau, and B. Weiss)  Descriptive Set Theory and Dynamical Systems , London Math. Soc. Lecture Note Series 277, 231-259, Cambridge University Press, 2000.
  • Descriptive Dynamics, in:  Descriptive Set Theory and Dynamical Systems, Ed. by M. Foreman et al., London Math. Soc. Lecture Note Series 277, 231-259, Cambridge University Press, 2000.
  • On the classification problem for rank 2 torsion-free abelian groups, J. London Math. Soc. 62(2) (2000), 437-450.
  • (with S. Adams) Linear algebraic groups and countable Borel equivalence relations, J. Amer. Math. Soc. 13(4) (2000), 909-943. 
  • (with R. Camerlo) Countable structures with a fixed group of automorphisms, Israel J. Math. 117 (2000), 105-124.
  • (with R. Dougherty) How many Turing degrees are there? in:  Computability Theory and Its Applications, Current Trends and Open Problems, Ed. by P.A. Cholak et al., Contemp. Math. 257, 83-94, Amer. Math. Soc., 2000.
  • (with G. Hjorth) The complexity of the classification of Riemann surfaces and complex manifolds, Ill. J. Math. 44(1) (2000), 104-137.
  • New directions in descriptive set theory, Bull. Symb. Logic 5(2) (1999), 161-174.>
  • (with A. Gordon) Measurable enumeration of eigenelements , Applicable Analysis 71 (1999), 41-62.
  • (with S. Solecki and S. Todorcevic) Borel chromatic numbers , Adv. in Math. 141 (1999), 1-44. 
  • The descriptive classification of some classes of C*-algebras , Proc. 6th Asian Logic Conference (C.T. Chong, et al., eds.) World Scientific, Singapore (1998), 121-149.
  • Rigidity properties of Borel ideals on the integers , Topology and Its Appl. 85 (1998), 195-205. 
  • (with G. Hjorth and A. Louveau) Borel equivalence relations induced by actions of the symmetric group , Ann. Pure and Appl. Logic 92 (1998), 63-112. 
  • On the concept of coanalytic-completeness , Proc. Amer. Math. Soc. 125(6) (1997), 1811-1814.
  • (with G. Hjorth) New dichotomies for Borel equivalence relations , Bull. Symb. Logic 3(3) (1997), 329-346. 
  • (with A. Louveau) The classification of hypersmooth Borel equivalence relations, J. Amer. Math. Soc. 10(1) (1997), 215-242.
  • Set theory and uniqueness for trigonometric series , preprint, 1997.  Click here for the  . pdf file
  • (with H. Becker) The Descriptive Set Theory of Polish Group Actions , London Math. Soc. Lecture Note Series, 232, Cambridge University Press, 1996. 
    • Corrections and Updates: click here for the . pdf file
  • (with G. Hjorth) Borel equivalence relations and classifications of countable models, Ann. Pure and Appl. Logic 82 (1996), 221-272.
  • (with G. Hjorth) Analytic equivalence relations and Ulm-type classifications , J. Symb. Logic 60 (1995), 1273-1300. 
  • Classical Descriptive Set Theory , Graduate Texts in Mathematics, 156, Springer, 1995.
    • Corrections and Updates: Click here for the . pdf file