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DTSTART:20170326T030000
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DTSTART:20171029T020000
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BEGIN:VEVENT
DTSTAMP:20260308T201332Z
UID:5853d1297be14689002361@ist.ac.at
DTSTART:20171024T160000
DTEND:20171024T180000
DESCRIPTION:Speaker: Dániel Virosztek\nhosted by Laszlo Erdös\nAbstract: 
 Given a set equipped with an additional structure (such as an algebraic op
 eration\, a distance-like measure of dissimilarity of the elements\, a rel
 ation\, etc.) the description of the transformations preserving this struc
 ture is of a particular importance. Such problems are called preserver pro
 blems. First\, we give a brief overview of the classical results in the fi
 eld of preserver problems (e.g.\, the Mazur-Ulam theorem\, and Wigner´s t
 heorem on the quantum mechanical symmetry transformations). Then we presen
 t some of our quite recent results on certain geometric preserver problems
  on (distinguished subsets of) positive matrices.In the second part of the
  talk we collect some classical statements that describe connections betwe
 en the commutativity of a C*-algebra and the basic properties (monotonicit
 y\, convexity) of certain functions defined on this C*-algebra by function
 al calculus.The starting point will be Ogasawara´s theorem which states t
 hat a C*-algebra is commutative if and only if the square function is mono
 tone increasing on the positive cone.Finally\, we will show some of our re
 cent results which describe connections between the centrality of an eleme
 nt of a C*-algebra and the local monotonicity and convexity properties of 
 certain functions.
LOCATION:Big Seminar room Ground floor / Office Bldg West (I21.EG.101)\, IS
 TA
ORGANIZER:jdeanton@ist.ac.at
SUMMARY:Dániel Virosztek: Preserver problems on positive matrices and char
 acterizations of central elements in C*-algebras
URL:https://talks-calendar.ista.ac.at/events/871
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