Hatcher-Algebraic-Topology · Problem 2B.8

Cohomology

Mathematics — Graph Theory · division-algebra-odd-dimension

Problem

Show that R2n+1\mathbb{R}^{2n+1} is not a division algebra over R\mathbb{R} if n>0n > 0 by considering how the determinant of the linear map x↦axx \mapsto ax given by the multiplication in a division algebra structure would vary as aa moves along a path in R2n+1−{0}\mathbb{R}^{2n+1} - \{0\} joining two antipodal points.

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