منابع مشابه
Extending Locally Truncated Buildings and Chamber Systems
Suppose we are given a building, or more generally a flag-geometry, and we remove all vertices of certain specified types, together with the flags containing such vertices. This is called truncating the geometry; precise definitions and an extension of this concept to chamber systems are given in (1.5). Given some flag-geometry all of whose residues are isomorphic to those of a truncated geomet...
متن کاملExtending locally truncated chamber systems by sheaves
We generalize the theory of sheaves to chamber systems. We prove that, given a chamber system C and a family R of proper residues of C containing all residues of rank c1, every sheaf defined over R admits a completion which extends C. We also prove that, under suitable hypotheses, a sheaf defined over a truncation of C can be extended to a sheaf for C. In the last section of this paper, we appl...
متن کاملA characterization of two classes of locally truncated diagram geometries
Let Γ = (P,L) be a parapolar space which is locally An−1,3(K) for some integer n > 6 and K a field. There exists a class of 2-convex subspaces D, each isomorphic to D5,5(K), such that every symplecton of Γ is contained in a unique element of D. Let Γ = (P,L) be a parapolar space which is locally An−1,4(K) for n = 7 or an integer n ≥ 9 and some field K. Assume that Γ satisfies the extra conditio...
متن کاملExtending dark optical trapping geometries.
New counterpropagating geometries are presented for localizing ultracold atoms in the dark regions created by the interference of Laguerre-Gaussian laser beams. In particular dark helices, an "optical revolver," axial lattices of rings, and axial lattices of ring lattices of rings are considered and a realistic scheme for achieving phase stability is explored. The dark nature of these traps wil...
متن کاملExtending Colorings of Locally
Suppose G is a graph embedded in S g with width (also known as edge width) at least 264(2 g ?1). If P V (G) is such that the distance between any two vertices in P is at least 16, then any 5-coloring of P extends to a 5-coloring of all of G. We present similar extension theorems for 6-and 7-chromatic toroidal graphs, for 3-colorable large-width graphs embedded on S g with every face even sided,...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series A
سال: 2001
ISSN: 0097-3165
DOI: 10.1006/jcta.2000.3138