منابع مشابه
Upper chromatic number of Steiner triple and quadruple systems
The upper chromatic number χ(H) of a set system H is the maximum number of colours that can be assigned to the elements of the underlying set of H in such a way that each H ∈ H contains a monochromatic pair of elements. We prove that a Steiner Triple System of order v ≤ 2 − 1 has an upper chromatic number which is at most k. This bound is the best possible, and the extremal configurations attai...
متن کامل5-Chromatic Steiner Triple Systems
We show that, up to an automorphism, there is a unique independent set in PG(5,2) that meet every hyperplane in 4 points or more. Using this result, we show that PG(5,2) is a 5-chromatic STS. Moreover, we construct a 5-chromatic STS(v) for every admissible v ≥ 127.
متن کاملThe existence of resolvable Steiner quadruple systems
A Steiner quadruple system of order v is a set X of cardinality v, and a set Q, of 4-subsets of X, called blocks, with the property that every 3-subset of X is contained in a unique block. A Steiner quadruple system is resolvable if Q can be partitioned into parallel classes (partitions of X). A necessary condition for the existence of a resolvable Steiner quadruple system is that v = 4 or 8 (m...
متن کاملAffine-invariant strictly cyclic Steiner quadruple systems
A Steiner quadruple system of order v, denoted by SQS(v), is a pair (V, B), where V is a finite set of v points, and B is a collection of 4-subsets of V , called blocks or quadruples, such that each 3-subset (triple) of V is contained in exactly one block in B. An automorphism group of SQS(v) is a permutation group on V leaving B invariant. An SQS(v) is said to be cyclic if it admits an automor...
متن کاملClassification of Flag-Transitive Steiner Quadruple Systems
A Steiner quadruple system of order v is a 3 − (v, 4, 1) design, and will be denoted SQS(v). Using the classification of finite 2-transitive permutation groups all SQS(v) with a flag-transitive automorphism group are completely classified, thus solving the ”still open and longstanding problem of classifying all flag-transitive 3− (v, k,1) designs” (cf. [5, p. 273], [6]) for the smallest value o...
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ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 1980
ISSN: 0195-6698
DOI: 10.1016/s0195-6698(80)80009-6