A formula for the number of Steiner quadruple systems on 2n points of 2‐rank 2n−n
Assmus  gave a description of the binary code spanned by the blocks of a Steiner triple or quadruple system according to the 2‐rank of the incidence matrix. Using this description, the author  found a formula for the total number of distinct Steiner triple systems on 2n−1 points of 2‐rank 2n ‐n. In this paper, a similar formula is found for the number of Steiner quadruple systems on 2n points of 2‐rank 2n ‐n. The formula can be used for deriving bounds on the number of pairwise non‐isomorphic systems for large n, and for the classification of all non‐isomorphic systems of small orders. The formula implies that the number of non‐isomorphic Steiner quadruple systems on 2n points of 2‐rank 2n ‐n grows exponentially. As an application, the Steiner quadruple systems on 16 points of 2‐rank 12 are classified up to isomorphism. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 260–274, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10036
Journal of Combinatorial Designs
A formula for the number of Steiner quadruple systems on 2n points of 2‐rank 2n−n.
Journal of Combinatorial Designs,
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