We study the hypergraph ~(P) whose vertices are the points of a finite poset and whose edges are the maximal intervals in P (i.e. sets of the form I = {v ~ P:p <~ v <<. q}, p minimal, q maximal). We mention resp. show that the problems of the determination of the independence number c~, the point co
Interval hypergraphs and D-interval hypergraphs
β Scribed by John I. Moore Jr.
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 449 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
A hypcrgraph H = ( ~,; g) is called an inler,, d hypergraph if there exists a one-try-one functio,~ [ mapping the elements of V h:~ points on the real line such that for each edge E, there is an interval !, containing the images of all elements of E, but not the images of any elements not in E,. The difference hypergraph D(H) determined by H is formed bv adding t:~ ~ all nonempty sets of the form E, -E,. where E, and E, are edges of H H is said to be a D-interval hypergraph if D(H) is an interval hypergraph. A forbidden subhypergraph characterization of D-interval hypergraphs is given. By relating D-interval hypergraphs to dimension theory for posets, ~ve determine all 3-irreducible 7~osets of length one.
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