Alexander Sotirios Kechris ( el, Αλέξανδρος Σωτήριος Κεχρής; born March 23, 1946) is a

set Set, The Set, SET or SETS may refer to: Science, technology, and mathematics Mathematics *Set (mathematics), a collection of elements *Category of sets, the category whose objects and morphisms are sets and total functions, respectively Electro ...

theorist and

logician Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...

at the

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

Contributions

Kechris has made contributions to the theory of

Borel equivalence relation In mathematics, a Borel equivalence relation on a Polish space ''X'' is an equivalence relation on ''X'' that is a Borel algebra, Borel subset of ''X'' × ''X'' (in the product topology). Formal definition Given Borel equivalence relation ...

s and the theory of

automorphism group In mathematics, the automorphism group of an object ''X'' is the group consisting of automorphisms of ''X'' under composition of morphisms. For example, if ''X'' is a finite-dimensional vector space, then the automorphism group of ''X'' is the g ...

s of

uncountable In mathematics, an uncountable set (or uncountably infinite set) is an infinite set that contains too many elements to be countable. The uncountability of a set is closely related to its cardinal number: a set is uncountable if its cardinal numb ...

structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

s. His research interests cover

foundations of mathematics Foundations of mathematics is the study of the philosophy, philosophical and logical and/or algorithmic basis of mathematics, or, in a broader sense, the mathematical investigation of what underlies the philosophical theories concerning the natu ...

, mathematical logic and set theory and their interactions with

analysis Analysis ( : analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (38 ...

and

dynamical systems In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in a p ...

. Kechris earned his

Ph.D. A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is a ...

at UCLA in 1972 under the direction of

Yiannis N. Moschovakis Yiannis Nicholas Moschovakis ( el, Γιάννης Μοσχοβάκης; born January 18, 1938) is a set theorist, descriptive set theorist, and recursion (computability) theorist, at UCLA. His book ''Descriptive Set Theory'' (North-Holland) is ...

, with a dissertation titled '' Projective Ordinals and

Countable In mathematics, a set is countable if either it is finite or it can be made in one to one correspondence with the set of natural numbers. Equivalently, a set is ''countable'' if there exists an injective function from it into the natural numbers; ...

Analytic Sets''. During his academic career he advised 23 PhD students and sponsored 20

postdoctoral researcher A postdoctoral fellow, postdoctoral researcher, or simply postdoc, is a person professionally conducting research after the completion of their doctoral studies (typically a PhD). The ultimate goal of a postdoctoral research position is to p ...

s. In 2012, he became an Inaugural Fellow of the

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

Honors

*1986 - Invited Speaker at the International Congress of Mathematicians in Berkeley (Mathematical Logic & Foundations) *1998 -

Gödel Lecture The Gödel Lecture is an honor in mathematical logic given by the Association for Symbolic Logic, associated with an annual lecture at the association's general meeting. The award is named after Kurt Gödel and has been given annually since 1990. ...

r (Current Trends in Descriptive Set Theory). *2003 - Received the

Karp Prize The Association for Symbolic Logic (ASL) is an international organization of specialists in mathematical logic and philosophical logic. The ASL was founded in 1936, and its first president was Alonzo Church. The current president of the ASL is ...

, along with Gregory Hjorth for joint work on Borel equivalence relations, in particular for their results on turbulence and countable

s *2004 - Tarski Lecturer (''New Connections Between Logic, Ramsey Theory and Topological Dynamics'')

Selected publications

* A. S. Kechris, "Classical Descriptive Set Theory", Springer-Verlag, 1995. * H. Becker, A. S. Kechris, "The descriptive set theory of Polish group actions" (London Mathematical Society Lecture Note Series), University of Cambridge, 1996. * A. S. Kechris, 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. * A. S. Kechris, "Global Aspects of Ergodic Group Actions", Mathematical Surveys and Monographs, 160, American Mathematical Society, 2010.

References

External links

A. S. Kechris biographical sketch

Kechris's web page at Caltech

American logicians Greek logicians 20th-century Greek mathematicians 21st-century Greek mathematicians California Institute of Technology faculty 1946 births Living people Set theorists Fellows of the American Mathematical Society Philosophers from California Gödel Lecturers {{Greece-mathematician-stub