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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. LOMI, 1987 Volume 157, Pages 23–29 (Mi znsl5188)

She multiplicity of some contractions

V. I. Vasyunin, M. T. Karaev


Abstract: for a unitary operator $U=U_a\oplus U_s$ for a $C_0$-contraction $T$, for the unilateral shift $S$ and for the backward shift $S^*$ the multiplicity of its direct sum is calculated:
$$ \mu_{(U\oplus S^n\oplus S^{*m}\oplus T)}=\max\{\mu_{U_s}, n+\max\{\mu_{U_a}, \mu_T, 1-\delta_{m0}\}\}, $$
where $\delta_{m0}=1$ if $m=0$ and $\delta_{m0}=0$ при $m>0$.

UDC: 517.984.48



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