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Simon Richárd: Preservers of the p-power and the Wasserstein means on 2x2 matrices

iCal fájl letöltése
Kedd, 18. Április 2023, 10:30 - 23:45
In one of his recent papers L. Molnár, On dissimilarities of the conventional and Kubo-Ando power means in operator algebras, (J. Math. Anal. Appl., 504 (2021) 125356), Molnár  showed that if A is a von Neumann algebra without  I1,I2-type direct summands,  then any function from the positive definite cone of A  to the positive real numbers preserving the Kubo-Ando power mean,  for some nonzero p between -1 and 1  is necessarily constant.
It was shown in that paper, that I1-type algebras admit nontrivial p-power  mean preserving functionals, and it was conjectured,  that I2-type algebras admit only constant p-power mean preserving functionals.
We  confirm the latter. A similar result occured in L. Molnár, Maps on positive definite cones of C-algebras preserving the Wasserstein mean, Proc. Amer. Math. Soc. 150 (2022), 1209-1221.,  concerning the Wasserstein mean. 
We prove the conjecture for I2-type algebras  in regard of the Wasserstein mean, too.  We also give two  conditions that characterise centrality in C-algebras.
Joint work with Dániel Virosztek.
 
The lecture will be in the Riesz lecture hall.

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