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Mathematics of Computation

Published by the American Mathematical Society since 1960 (published as Mathematical Tables and other Aids to Computation 1943-1959), Mathematics of Computation is devoted to research articles of the highest quality in computational mathematics.

ISSN 1088-6842 (online) ISSN 0025-5718 (print)

The 2020 MCQ for Mathematics of Computation is 1.78.

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Reductions of operator pencils
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by Olivier Verdier PDF
Math. Comp. 83 (2014), 189-214 Request permission

Abstract:

We study problems associated with an operator pencil, i.e., a pair of operators on Banach spaces. Two natural problems to consider are linear constrained differential equations and the description of the generalized spectrum. The main tool to tackle either of those problems is the reduction of the pencil. There are two kinds of natural reduction operations associated to a pencil, which are conjugate to each other.

Our main result is that those two kinds of reductions commute, under some mild assumptions that we investigate thoroughly.

Each reduction exhibits moreover a pivot operator. The invertibility of all the pivot operators of all possible successive reductions corresponds to the notion of regular pencil in the finite dimensional case, and to the inf-sup condition for saddle point problems on Hilbert spaces.

Finally, we show how to use the reduction and the pivot operators to describe the generalized spectrum of the pencil.

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Additional Information
  • Olivier Verdier
  • Affiliation: Department of Mathematical Sciences, NTNU, 7491 Trondheim, Norway
  • MR Author ID: 873226
  • Email: olivier.verdier@math.ntnu.no
  • Received by editor(s): May 27, 2011
  • Received by editor(s) in revised form: May 22, 2012
  • Published electronically: June 27, 2013
  • © Copyright 2013 American Mathematical Society
    The copyright for this article reverts to public domain 28 years after publication.
  • Journal: Math. Comp. 83 (2014), 189-214
  • MSC (2010): Primary 15A21, 15A22, 34A30, 47A10, 65L80
  • DOI: https://doi.org/10.1090/S0025-5718-2013-02740-8
  • MathSciNet review: 3120586