# L. B. Turowska

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Articles: 7

### On the spectrum of multiplication operators

Methods Funct. Anal. Topology 24 (2018), no. 3, 265-274

We study relations between spectra of two operators that are connected to each other through some intertwining conditions. As an application, we obtain new results on the spectra of multiplication operators on $B(\mathcal H)$ relating it to the spectra of the restriction of the operators to the ideal $\mathcal C_2$ of Hilbert-Schmidt operators. We also solve one of the problems, posed in [6], about the positivity of the spectrum of multiplication operators with positive operator coefficients when the coefficients on one side commute. Using the Wiener-Pitt phenomena we show that the spectrum of a multiplication operator with normal coefficients satisfying the Haagerup condition might be strictly larger than the spectrum of its restriction to $\mathcal C_2$.

### On well-behaved representations of $\lambda$-deformed CCR

Methods Funct. Anal. Topology 23 (2017), no. 2, 192-205

We study well-behaved ∗-representations of a λ-deformation of Wick analog of CCR algebra. Homogeneous Wick ideals of degrees two and three are described. Well-behaved irreducible ∗-representations of quotients by these ideals are classified up to unitary equivalence.

### On bounded and unbounded idempotents whose sum is a multiple of the identity

Methods Funct. Anal. Topology 8 (2002), no. 1, 79-100

### Existence and unicity of $\sigma$-forms on finite-dimensional modules

Methods Funct. Anal. Topology 7 (2001), no. 1, 53-62

### On C*-algebra associated with ${\rm Pol}({\rm Mat}_ {2,2})_q$

Methods Funct. Anal. Topology 7 (2001), no. 1, 88-92

### Representations of double commutator by matrix-differential operators

Methods Funct. Anal. Topology 3 (1997), no. 3, 75-80

### Semilinear relations and their $*$-representations

Methods Funct. Anal. Topology 2 (1996), no. 1, 55-111