There are 80 non-isomorphic Steiner triple systems of order 15. A standard listing of these is given in Mathon et al. (1983, Ars Combin., 15, 3-110). We prove that systems #1 and #2 have no bi-embedding together in an orientable surface. This is the first known example of a pair of Steiner triple sy
Another complete invariant for Steiner triple systems of order 15
✍ Scribed by Olivier Anglada; Jean-François Maurras
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 64 KB
- Volume
- 13
- Category
- Article
- ISSN
- 1063-8539
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✦ Synopsis
Abstract
In this note, the 80 non‐isomorphic triple systems on 15 points are revisited from the viewpoint of the convex hull of the characteristic vectors of their blocks. The main observation is that the numbers, of facets of these 80 polyhedra are all different, thus producing a new proof of the non‐isomorphism of these triple systems. The space dimension of these polyhedra is also discussed. Finally, we observe the large number of facets of some of these polyhedra with few vertices, in relation with the upper bound problem for combinatorial polyhedra. © 2005 Wiley Periodicals, Inc. J Combin Designs.
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## Abstract The codewords at distance three from a particular codeword of a perfect binary one‐error‐correcting code (of length 2^m^−1) form a Steiner triple system. It is a longstanding open problem whether every Steiner triple system of order 2^m^−1 occurs in a perfect code. It turns out that thi