Multi-valued functions, fixed points, and applications
Main researcher
: ČERIN, ZVONKO (7994) Assistants
Type of research: basic Duration from: 01/01/91. to 12/31/96. Papers on project (total): 22
Papers on project quoted in Current Contents: 22
Institution name: Prirodoslovno-matematički fakultet, Matematički odjel, Zagreb (37) Department/Institute: Department of Mathematics Faculty of Natural Sciences University of Zagreb Address: Bijenička cesta 30 City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 678 411
Fax: 385 (0)1 432 484
E-mail: zcerin@x400.srce.hr
E-mail: cerin@cromath.math.hr
Summary: In this fundamental research in mathematics we consider
some areas in topology in order to contribute to our understanding of
this important field of mathematics. The present day mathematics can
roughly be divided into three major fields: algebra, analysis, and
topology. In algebra we manipulate numbers (adding, multiplying,
dividing,...), in analysis we analyse functions (we take derivatives,
integrals,.., solve diferential equations,...), while in topology we study
the structure of spaces and processes with respect to continuity that
plays the key role (we look for limits, investigate continuous
functions,...). These three fields are today so much entwined and
interdependent that it is all too common that a discovery say in analysis
is made using results and techniques of both algebra and topology and vice
versa. It is therefore natural and wise to consider all three equally
valuable and important for the healthy development of all sciences.
Our contribution to topology relates to the existence of fixed points and
coincidence points for continuous functions and the application of
multi-valued functions in topology. In the period 91-95 working on a
project twentytwo original research articles on the above topics were
published in renown international journals on over 410 printed pages and
several others have been accepted for publication.
Keywords: mathematics, topology, continuous function, multi-valued function, fixed point, coincidence point, universal map (in the sense of Holsztynski), shape theory, proper shape theory, C*-algebra
Research goals: The first goal of this project is to study the
class of universal maps that was introduced in sixties by a Polish
mathematician Holsztynski. The universality of this maps refers to the fact
that they have a coincidence point with every other map. This interesting
class of maps has not been studied extensively so far inspite of their
close connection with the fixed point theory which is one of the parts of
topology that had numerous applications elsewhere. The second goal is
to find applications of universal maps in mathematical economics analogous
to the way how fixed point theory has been used in equilibrium theory of
economies and regulated societies. We hope to contribute to searches for
optimal economy models for post-communist countries. The third goal is
to improve the existing fixed point theorems (the one of Lefschetz in
particular) by enlarging the class of spaces to which this algebraic
method of location of fixed points is applicable. We shall also try to
obtain versions of these results for multi-valued functions. The
fourth and the most important goal is to look for applications of
multi-valued functions in topology which will provide new results and lead
to improvement of known results. We shall attempt to describe various
types of shape theories using multi-valued functions with smaller and
smaller images of points analogous to the recent description of shape
theory of compact metric spaces by J. Sanjurjo. The expected results
is hard to predict. However, I believe that I will menage to prepare
several articles on these topics. Whether, where, and when they get
published is impossible to forsee.
COOPERATION - INSTITUTIONS
Name of institution
: Universita di Torino
Dipartimento di Matematica Torino,
Italia Type of institution: University/Faculty Type of cooperation: Joint publishing of scientific papers City: 11233 - Torino, Italija
Name of institution
: Universita di Messina
Dipartimento di Matematica Messina,
Italia Type of institution: University/Faculty Type of cooperation: Joint publishing of scientific papers City: 98166 - Messina IT, Italija
OTHER ACHIEVEMENTS
Name
: "Proper shape theory"
predavanje na znanstvenom skupu "Colloquium on Topology", Szeksard,
Mađarska, August 22-28, 1993. Type of achievement: Other Authors: Zvonko Čerin
Name
: "Shape theory intrinsically"
predavanje na znanstvenom skupu "11-th Italian International Topology
Meeting", Trieste, Italia, Septembar 6-11, 1993. Type of achievement: Other Authors: Zvonko Čerin