Lomonosov's invariant subspace theorem

Lomonosov's invariant subspace theorem is a mathematical theorem from functional analysis concerning the existence of invariant subspaces of a linear operator on some complex Banach space. The theorem was proved in 1973 by the Russian–American mathematician Victor Lomonosov.[1]

Lomonosov's invariant subspace theorem

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Notation and terminology

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Let   be the space of bounded linear operators from some space   to itself. For an operator   we call a closed subspace   an invariant subspace if  , i.e.   for every  .

Theorem

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Let   be an infinite dimensional complex Banach space,   be compact and such that  . Further let   be an operator that commutes with  . Then there exist an invariant subspace   of the operator  , i.e.  .[2]

Citations

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  1. ^ Lomonosov, Victor I. (1973). "Invariant subspaces for the family of operators which commute with a completely continuous operator". Functional Analysis and Its Applications. 7: 213–214.
  2. ^ Rudin, Walter. Functional Analysis. McGraw-Hill Science/Engineering/Math. p. 269-270. ISBN 978-0070542365.

References

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