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Représentations de semi-groupes de mesures sur un groupe localement compact

Michel Duflo (1978)

Annales de l'institut Fourier

Soit T une distribution dissipative sur un groupe de Lie G et soit π une représentation fortement continue de G dans un espace de Banach. Supposons T à support compact. Il y a deux façons évidentes de définir un opérateur fermé π ( T ) : une faible et une forte. Le résultat principal de cet article est que l’on obtient le même résultat et que π ( T ) engendre un semi-groupe fortement continu d’opérateurs.

Semibounded Unitary Representations of Double Extensions of Hilbert–Loop Groups

K. H. Neeb (2014)

Annales de l’institut Fourier

A unitary representation π of a, possibly infinite dimensional, Lie group G is called semibounded if the corresponding operators i d π ( x ) from the derived representation are uniformly bounded from above on some non-empty open subset of the Lie algebra 𝔤 of G . We classify all irreducible semibounded representations of the groups ^ φ ( K ) which are double extensions of the twisted loop group φ ( K ) , where K is a simple Hilbert–Lie group (in the sense that the scalar product on its Lie algebra is invariant) and φ is...

Spectra of elements in the group ring of SU(2)

Alex Gamburd, Dmitry Jakobson, Peter Sarnak (1999)

Journal of the European Mathematical Society

We present a new method for establishing the ‘‘gap” property for finitely generated subgroups of SU ( 2 ) , providing an elementary solution of Ruziewicz problem on S 2 as well as giving many new examples of finitely generated subgroups of SU ( 2 ) with an explicit gap. The distribution of the eigenvalues of the elements of the group ring 𝐑 [ SU ( 2 ) ] in the N -th irreducible representation of SU ( 2 ) is also studied. Numerical experiments indicate that for a generic (in measure) element of 𝐑 [ SU ( 2 ) ] , the “unfolded” consecutive spacings...

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