O ct 2 00 5 Angle structures and normal surfaces
نویسنده
چکیده
Let M be the interior of a compact 3–manifold with non–empty boundary, and T be an ideal (topological) triangulation of M . This paper describes necessary and sufficient conditions for the existence of angle structures, semi–angle structures and generalised angle structures on (M ; T ) respectively in terms of a generalised Euler characteristic function on the solution space of normal surface theory of (M ; T ). This extends previous work of Kang and Rubinstein, and is itself generalised to a more general setting for 3–dimensional pseudo-manifolds. AMS Classification 57M25, 57N10
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