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Circular operators related to some quantum observables

Wacław Szymański (1997)

Annales Polonici Mathematici

Circular operators related to the operator of multiplication by a homomorphism of a locally compact abelian group and its restrictions are completely characterized. As particular cases descriptions of circular operators related to various quantum observables are given.

Criterion of p -criticality for one term 2 n -order difference operators

Petr Hasil (2011)

Archivum Mathematicum

We investigate the criticality of the one term 2 n -order difference operators l ( y ) k = Δ n ( r k Δ n y k ) . We explicitly determine the recessive and the dominant system of solutions of the equation l ( y ) k = 0 . Using their structure we prove a criticality criterion.

Differentiable L p -functional calculus for certain sums of non-commuting operators

Michael Gnewuch (2006)

Colloquium Mathematicae

We consider a special class of sums of non-commuting positive operators on L²-spaces and derive a formula for their holomorphic semigroups. The formula enables us to give sufficient conditions for these operators to admit differentiable L p -functional calculus for 1 ≤ p ≤ ∞. Our results are in particular applicable to certain sub-Laplacians, Schrödinger operators and sums of even powers of vector fields on solvable Lie groups with exponential volume growth.

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