Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4668092 | Advances in Mathematics | 2007 | 13 Pages |
Abstract
Let A be a nonempty real central arrangement of hyperplanes and Ch be the set of chambers of A. Each hyperplane H defines a half-space H+ and the other half-space H−. Let B={+,−}. For H∈A, define a map by (if C⊆H+) and (if C⊆H−). Define . Let Chm=Ch×Ch×⋯×Ch (m times). Then the maps induce the maps . We will study the admissible maps which are compatible with every . Suppose |A|⩾3 and m⩾2. Then we will show that A is indecomposable if and only if every admissible map is a projection to a component. When A is a braid arrangement, which is indecomposable, this result is equivalent to Arrow's impossibility theorem in economics. We also determine the set of admissible maps explicitly for every nonempty real central arrangement.
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