## Abstract The obvious necessary conditions for the existence of a nested Steiner triple system of order __v__ containing a nested subsystem of order __w__ are __v__ββ₯β3__w__β+β4 and __v__ββ‘βwββ‘β1 (mod 6). We show that these conditions are also sufficient. Β© 2004 Wiley Periodicals, Inc.
A special class of nested Steiner triple systems
β Scribed by Darryn E. Bryant
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 219 KB
- Volume
- 152
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
There exists a pair of (v, 4, 1)-BIBD's, with block sets B 1 and B 2 , such that it is possible to obtain a Steiner triple system by removing a point from each block in B 1 U B 2 if and only if v == 1 (mod 12). A Steiner triple system of order v (denoted STS(v)) is a (v, 3, 1)-BlBD. A nested Steiner triple system of order v (denoted NSTS(v)) is an STS(v) with an extra point added to each block in such a way that the resulting blocks form a (v, 4, 2)-BlBD. After several earlier papers on NSTS's (see e.g. [2,3] Stinson [4] constructed NSTS(v)'s for each v == 1 (mod 6). It is easy to see that v == 1 (mod 6) is necessary.
In this paper, we consider a special class of NSTS(v)'s; those in which the (v, 4, 2)-BlBD can be partitioned into two (v, 4, 1)-BlBD's. These will be called partitionable nested Steiner triple systems.
π SIMILAR VOLUMES
## Abstract A 2βclass regular partial Steiner triple system is a partial Steiner triple system whose points can be partitioned into 2βclasses such that no triple is contained in either class and any two points belonging to the same class are contained in the same number of triples. It is uniform if
Phelps, K.T. and C.A. Rodger, Nesting partial Steiner triple systems with 2-regular leave graphs, Discrete Mathematics 112 (1993) 1655172. In this paper we consider the problem of nesting partial Steiner triple systems. Among other results, we show that if there exists a nesting of a partial Steine
If X is a set whose elements are called points and A is a collectioxr of subsets of X (called lines) such that: (i) any two distinct points of X are contained in exactly one line, (ii) every line contains at least two points, we say that the pair (X, A) is a linear space. A Steiner triple system i
## Abstract In this paper, we present three constructions for antiβmitre Steiner triple systems and a construction for 5βsparse ones. The first construction for antiβmitre STSs settles two of the four unsettled admissible residue classes modulo 18 and the second construction covers such a class mod