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6.175  Articles
1 of 619 pages  |  10  records  |  more records»
In this paper, we investigate the limit points set of essential spectrum of upper triangular operator matricesWe prove that accse(MC) ? W = accse(A) ? accse(B) where W is the union of certain holes in accse(MC), which happen to be subsets of accse(B) n ac... see more

In this paper, we investigate the limit points set of surjective and approximate point spectra of upper triangular operator matrices . We prove that s*(MC) ? W=s*(A)? s*(B) where W is the union of certain holes in s*(MC), which happen to be subsets of s l... see more

Hyponormal operators are necessarily posinormal, but they need not be coposinormal.  Coposinormality can nevertheless sometimes be an aid in determining hyponormality.  This idea is applied to coposinormal factorable matrices whose interrupter i... see more

In this paper we prove some upper and lower bounds for the numerical radius of the off-diagonal part of 3 X 3 operator matrices and some bounds for the numerical radius inequalities of the general 3 X 3 operator matrix.

Some summability results are established for matrices of quasihomogeneous operators by uniformly vanishing sets.

We count invertible Schrödinger operators (perturbations by diagonal matrices of the adjacency matrix) over finite fields for trees, cycles and complete graphs. This is achieved for trees through the definition and use of local invariants (algebraic const... see more

Hyponormal operators are necessarily posinormal, but they need not be coposinormal.  Coposinormality can nevertheless sometimes be an aid in determining hyponormality.  This idea is applied to coposinormal factorable matrices whose interrupter i... see more

Alternating sign matrices are known to be equinumerous with descending plane partitions, totally symmetric self-complementary plane partitions and alternating sign triangles, but no bijective proof for any of these equivalences has been found so far. In t... see more

In this paper, we define (s, 0)-convergence and characterize (s, ?)-conservative, (s, 0)-regular, (s, 0)-coercive matrices and we also determine the associated bounded linear operators for these matrix classes.

1 of 619 pages  |  10  records  |  more records»