Almost all Steiner triple systems are almost resolvable
نویسندگان
چکیده
منابع مشابه
Almost all cancellative triple systems are tripartite
A triple system is cancellative if no three of its distinct edges satisfy A ∪ B = A ∪ C. It is tripartite if it has a vertex partition into three parts such that every edge has exactly one point in each part. It is easy to see that every tripartite triple system is cancellative. We prove that almost all cancellative triple systems with vertex set [n] are tripartite. This sharpens a theorem of N...
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The neighborhood of a pair of vertices u, v in a triple system is the set of vertices w such that uvw is an edge. A triple system H is semi-bipartite if its vertex set contains a vertex subset X such that every edge of H intersects X in exactly two points. It is easy to see that if H is semi-bipartite, then the neighborhood of every pair of vertices in H is an independent set. We show a partial...
متن کاملAlmost all triangle-free triple systems are tripartite
A triangle in a triple system is a collection of three edges isomorphic to {123, 124, 345}. A triple system is triangle-free if it contains no three edges forming a triangle. It is tripartite if it has a vertex partition into three parts such that every edge has exactly one point in each part. It is easy to see that every tripartite triple system is triangle-free. We prove that almost all trian...
متن کامل5-sparse Steiner Triple Systems of Order n Exist for Almost All Admissible n
Steiner triple systems are known to exist for orders n ≡ 1, 3 mod 6, the admissible orders. There are many known constructions for infinite classes of Steiner triple systems. However, Steiner triple systems that lack prescribed configurations are harder to find. This paper gives a proof that the spectrum of orders of 5-sparse Steiner triple systems has arithmetic density 1 as compared to the ad...
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ژورنال
عنوان ژورنال: Forum of Mathematics, Sigma
سال: 2020
ISSN: 2050-5094
DOI: 10.1017/fms.2020.29