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Jun 30, 2018
06/18

by
Markus Seidel

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In this paper we study the semi-Fredholm property of band-dominated operators $A$ and prove that it already implies the Fredholmness of $A$ in all cases where this is not disqualified by obvious reasons. Moreover, this observation is applied to show that the Fredholmness of a band-dominated operator already follows from the surjectivity of all its limit operators.

Topics: Functional Analysis, Mathematics

Source: http://arxiv.org/abs/1407.8104

2
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Jun 30, 2018
06/18

by
Marko Lindner; Markus Seidel

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An operator on an $l^{p}$-space is called band-dominated if it can be approximated, in the operator norm, by operators with a banded matrix representation. It is known that a rich band-dominated operator is $\mathcal{P}$-Fredholm (which is a generalization of the classical Fredholm property) if and only if all of its so-called limit operators are invertible and their inverses are uniformly bounded. We show that the condition on uniform boundedness is redundant in this statement.

Topics: Functional Analysis, Mathematics, Operator Algebras

Source: http://arxiv.org/abs/1401.1300

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Jun 27, 2018
06/18

by
Raffael Hagger; Marko Lindner; Markus Seidel

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An operator $A$ on an $l^p$-space is called band-dominated if it can be approximated, in the operator norm, by operators with a banded matrix representation. The coset of $A$ in the Calkin algebra determines, for example, the Fredholmness of $A$, the Fredholm index, the essential spectrum, the essential norm and the so-called essential pseudospectrum of $A$. This coset can be identified with the collection of all so-called limit operators of $A$. It is known that this identification preserves...

Topics: Functional Analysis, Operator Algebras, Mathematics

Source: http://arxiv.org/abs/1504.00540

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Jun 30, 2018
06/18

by
Markus Seidel; for the ATLAS; CMS Collaborations

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The ATLAS and CMS collaborations at the Large Hadron Collider (LHC) are studying the top quark in pp collisions at 7 and 8 TeV. Due to the large integrated luminosity, precision measurements of production cross-sections and properties are often limited by systematic uncertainties. An overview of the modeling uncertainties for simulated events is given in this report.

Topics: High Energy Physics - Phenomenology, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1410.6994

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Jun 28, 2018
06/18

by
Jonathan Ben-Artzi; Anders C. Hansen; Olavi Nevanlinna; Markus Seidel

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This paper establishes some of the fundamental barriers in the theory of computations and finally settles the long standing computational spectral problem. Due to these barriers, there are problems at the heart of computational theory that do not fit into classical complexity theory. Many computational problems can be solved as follows: a sequence of approximations is created by an algorithm, and the solution to the problem is the limit of this sequence. However, as we demonstrate, for several...

Topics: Computational Complexity, Mathematical Physics, Logic, Spectral Theory, Computing Research...

Source: http://arxiv.org/abs/1508.03280