Classification of Finite Spaces of Orderings

Canadian Journal of Mathematics - Tập 31 Số 2 - Trang 320-330 - 1979
Murray Marshall1
1University of Saskatchewan, Saskatoon, Saskatchewan

Tóm tắt

1. Introduction. A space of orderings will refer to what was called a “set of quasi-orderings” in [5]. That is, a space of orderings is a pair (X, G) where G is an elementary 2-group (i.e. x2 = 1 for all x ∈ G) with a distinguished element – 1 ∈ G, and X is a subset of the character group x(G) = Horn (G, {1, –1};) satisfying the following properties:01: X is a closed subset of χ(G).02: σ(−l) = −1 holds for all σ ∊ X.03: X⊥ = {a ∊ G|χa = 1 for all a ∊ X} = 1.04: If f and g are forms over G and if x ∊ Df⊗g, then there exist y ∊ Df and z ∊ Dg such that x ∊ D(y, z).

Từ khóa


Tài liệu tham khảo

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Thông tin
Thông tin xuất bản

Canadian Journal of Mathematics

Tập 31 Số 2

320-330

Thông tin tác giả