A spatial form of the spectralradius formula for matrices
Speaker 
Soumyashant Nayak (ISI Bangalore)


When 
Apr 11, 2023
from 02:00 PM to 03:00 PM 
Where  Auditorium, Ground Floor, TIFR CAM, Bangalore 
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Abstract: For an m x m complex matrix A, we will discuss the limiting behaviour of the matrix sequence { A^n^(1/n) } and provide a stronger form of Yamamoto's theorem which asserts that s_j(A^n)^(1/n) tends to the jthlargest eigenvaluemodulus of A, where s_j(A^n) denotes the jthlargest singular value of A^n (j=1 gives us the spectral radius formula). This also tells us about the limiting behaviour of the sequence { g^n^(1/n)} for an element g in a real noncompact semsimple Lie group with a given Cartan involution. Towards the end, we will discuss connections with the invariant subspace problem and discuss the difficulties in studying the limiting behaviour of such sequences when A is a bounded operator on an infinitedimensional Hilbert space.