Grassmann Homomorphism and Hajós-type Theorems
نویسنده
چکیده
Let V and W be vector spaces over a common field, and let S and T be sets of subspaces of V and W, respectively. A linear function φ : V → W is called a (Grassmann) homomorphism from S to T if φ(S) ∈ T holds for every S ∈ S. Coloring of graphs and hypergraphs and flows in graphs can be reformulated in terms of these homomorphisms. The main results are constructive characterizations of the sets S of lines for which there is no homomorphism from S to a singleton set T with a line as its element.
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تاریخ انتشار 2017