Results 1 to 10 of about 4,469,777 (359)
Spectrum of a Composition Operator [PDF]
Proceedings of the American Mathematical Society, 1973 A composition operator is a linear operator induced on a subspace of K X {K^X} by a point transformation ϕ \phi on a set X (where K denotes the scalar field) by the formula T f ( x ) = f ∘ ϕ ( x )
William C. Ridge
semanticscholar +3 more sources
Subnormal composition operators [PDF]
Proceedings of the American Mathematical Society, 1988 Let C C be the composition operator on L 2 ( X , Σ , m ) {L^2}(X,\Sigma ,m) given by C f = f ∘ T Cf = f \circ T , where T T is a Σ
Alan Lambert
openalex +2 more sources
Composition of maximal operators [PDF]
Publicacions Matemàtiques, 1996 Consider the Hardy-Littlewood maximal operator $$ Mf(x)=\sup_{Q\owns x}\frac{1}{|Q|}\int_Q |f(y)|\,dy. $$ It is known that $M$ applied to $f$ twice is pointwise comparable to the maximal operator $M_{L\log L}f$, defined by replacing the mean value of $|f|$ over the cube $Q$ by the $L\log L$-mean, namely $$ M_{L\log L}f(x)=\sup_{x\in Q} \frac{1}{|Q ...
M. Carozza +1 more
openaire +7 more sources
Composite operators near the boundary [PDF]
Journal of High Energy Physics, 2020 Abstract We use renormalization group methods to study composite operators existing at a boundary of an interacting conformal field theory. In particular we relate the data on boundary operators to short-distance (near-boundary) divergences of bulk two-point functions.
Vladimír Procházka +1 more
openaire +4 more sources
Renormalization of composite operators [PDF]
Physical Review D, 2001 The blocked composite operators are defined in the one-component Euclidean scalar field theory, and shown to generate a linear transformation of the operators, the operator mixing. This transformation allows us to introduce the parallel transport of the operators along the RG trajectory. The connection on this one-dimensional manifold governs the scale
Janos Polonyi +2 more
openaire +3 more sources
Extended eigenvalues of composition operators
Journal of Mathematical Analysis and Applications, 2021 A complex scalar λ is said to be an extended eigenvalue of a bounded linear operator A on a complex Hilbert space if there is a nonzero operator X such that . The results in this paper provide a full solution to the problem of computing the extended eigenvalues for those composition operators induced on the Hardy space by linear fractional ...
Miguel Lacruz +3 more
openaire +5 more sources
Composition Operators and Endomorphisms [PDF]
Complex Analysis and Operator Theory, 2010 If $b$ is an inner function, then composition with $b$ induces an endomorphism, $ $, of $L^\infty(\mathbb{T})$ that leaves $H^\infty(\mathbb{T})$ invariant. We investigate the structure of the endomorphisms of $B(L^2(\mathbb{T}))$ and $B(H^2(\mathbb{T}))$ that implement $ $ through the representations of $L^\infty(\mathbb{T})$ and $H^\infty(\mathbb{T}
Paul S. Muhly +2 more
openaire +3 more sources
Universal composition operators
Journal of Operator Theory, 2021 A Hilbert space operator U is called \textit{universal} (in the sense of Rota) if every Hilbert space operator is similar to a multiple of U restricted to one of its invariant subspaces. It follows that the \textit{invariant subspace problem} for Hilbert spaces is equivalent to the statement that all minimal invariant subspaces for U are one ...
Carmo, João R., Noor, S. Waleed
openaire +2 more sources
Compact composition operators on the Dirichlet space and capacity of sets of contact points [PDF]
, 2012 In this paper, we prove that for every compact set of the unit disk of logarithmic capacity 0, there exists a Schur function both in the disk algebra and in the Dirichlet space such that the associated composition operator is in all Schatten classes (of ...
Lefèvre, Pascal +3 more
core +3 more sources
Weighted composition operators as Daugavet centers [PDF]
, 2009 We investigate the norm identity $\|uC_\phi + T\| = \|u\|_\infty + \|T\|$ for classes of operators on $C(S)$, where $S$ is a compact Hausdorff space without isolated point, and characterize those weighted composition operators which satisfy this equation
Demazeux, Romain
core +4 more sources