151. The Borsuk-Ulam theorem for 3-manifolds
- Author
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Chahrazade Matmat and Christian Blanchet
- Subjects
Mathematics::Functional Analysis ,Mathematics::General Topology ,Borsuk–Ulam theorem ,Mathematics::Algebraic Topology ,Nonlinear Sciences::Chaotic Dynamics ,Combinatorics ,Mathematics (miscellaneous) ,FOS: Mathematics ,Mathematics::Metric Geometry ,Algebraic Topology (math.AT) ,Involution (philosophy) ,57K30, 57M60 ,Mathematics - Algebraic Topology ,Value (mathematics) ,Mathematics - Abstract
We study the Borsuk-Ulam theorem for triple (M;\tau; \R^n), where M is a compact, connected, 3-manifold equipped with a fixed-point-free involution \tau. The largest value of n for which the Borsuk-Ulam theorem holds is called the Z_2-index and in our case it takes value 1, 2 or 3. We fully discuss this index according to cohomological operations applied on the characteristic class x \in H^1(N; Z_2), where N = M/\tau is the orbit space. In oriented case, we obtain an expression of the index from the linking matrix of a surgery presentation of the orbit space. We illustrate our results with examples, including a non orientable one.
- Published
- 2020
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