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Full-Text Articles in Physical Sciences and Mathematics
Bohr Density Of Simple Linear Group Orbits, Roger Howe, François Ziegler
Bohr Density Of Simple Linear Group Orbits, Roger Howe, François Ziegler
François Ziegler
We show that any non-zero orbit under a non-compact, simple, irreducible linear group is dense in the Bohr compactification of the ambient space.
Primary Spaces, Mackey’S Obstruction, And The Generalized Barycentric Decomposition, Patrick Iglesias-Zemmour, François Ziegler
Primary Spaces, Mackey’S Obstruction, And The Generalized Barycentric Decomposition, Patrick Iglesias-Zemmour, François Ziegler
François Ziegler
We call a hamiltonian N-space primary if its moment map is onto a single coadjoint orbit. The question has long been open whether such spaces always split as (homogeneous) × (trivial), as an analogy with representation theory might suggest. For instance, Souriau’s barycentric decomposition theorem asserts just this when N is a Heisenberg group. For general N, we give explicit examples which do not split, and show instead that primary spaces are always flat bundles over the coadjoint orbit. This provides the missing piece for a full “Mackey theory” of hamiltonian G-spaces, where G is an overgroup in which N …