منابع مشابه
On Nearly Semifree Circle Actions
Recall that an effective circle action is semifree if the stabilizer subgroup of each point is connected. We show that if (M,ω) is a coadjoint orbit of a compact Lie group G then every element of π1(G) may be represented by a semifree S-action. A theorem of McDuff– Slimowitz then implies that π1(G) injects into π1(Ham(M,ω)), which answers a question raised by Weinstein. We also show that a circ...
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We study countable universes similar to a free action of a group G. It turns out that this is equivalent to the study of free semi-actions of G, with two universes being transformable iff one corresponding free semi-action can be obtained from the other by a finite alteration. In the case of a free group G (in finitely many or countably many generators), a classification is given. Mathematics S...
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A theorem of Tolman and Weitsman states that all symplectic semifree circle actions with isolated fixed points on compact symplectic manifolds must be Hamiltonian and have the same equivariant cohomology and Chern classes of (CP 1)n equipped with the standard diagonal circle action. In this paper, we show that the situation is much different when we consider compact symplectic orbifolds. Focusi...
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The structure and modular properties of N = 4 superconformal characters are reviewed and exploited, in an attempt to construct elliptic genera-like functions by decompactifying K3. The construction is tested against expressions obtained in the context of strings propagating in background ALE spaces of type AN−1, using the underlying superconformal theory N = 2 minimal ⊗ N = 2 Liouville.
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Let M be a closed almost complex manifold on which a compact connected Lie group G acts non-trivially. If the first Chern class of M is divisible by an integer N greater than 1, then its equivariant elliptic genus φ(M) of level N is rigid, i.e., it is constant as a virtual character of G. This result was predicted by Witten [W] and proved by Taubes [T], Bott-Taubes [BT] and Hirzebruch [H]. Elli...
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ژورنال
عنوان ژورنال: Topology and its Applications
سال: 1996
ISSN: 0166-8641
DOI: 10.1016/0166-8641(96)00010-7