Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-26T01:13:57.286Z Has data issue: false hasContentIssue false

Strongly Regular Graphs Derived from Combinatorial Designs

Published online by Cambridge University Press:  20 November 2018

J. M. Goethals
Affiliation:
M.B.L.E. Research Laboratory, Brussels, Belgium
J. J. Seidel
Affiliation:
Technological University, Eindhoven, Netherlands
Rights & Permissions [Opens in a new window]

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Several concepts in discrete mathematics such as block designs, Latin squares, Hadamard matrices, tactical configurations, errorcorrecting codes, geometric configurations, finite groups, and graphs are by no means independent. Combinations of these notions may serve the development of any one of them, and sometimes reveal hidden interrelations. In the present paper a central role in this respect is played by the notion of strongly regular graph, the definition of which is recalled below.

In § 2, a fibre-type construction for graphs is given which, applied to block designs with λ = 1 and Hadamard matrices, yields strongly regular graphs. The method, although still limited in its applications, may serve further developments. In § 3 we deal with block designs, first considered by Shrikhande [22], in which the number of points in the intersection of any pair of blocks attains only two values.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1970

References

1. Assmus, E. F. and Mattson, H. F., On tactical configurations and error-correcting codes, J. Combinatorial Theory 2 (1967), 243257.Google Scholar
2. Bose, R. C., Strongly regular graphs, partial geometries and partially balanced designs, Pacific J. Math. 13 (1963), 389419.Google Scholar
3. Ehlich, H., Neue Hadamard-Matrizen, Arch. Math. 16 (1965), 3436.Google Scholar
4. Gewirtz, A., Graphs with maximal even girth, Can. J. Math. 21 (1969), 915934.Google Scholar
5. Gewirtz, A., The uniqueness ofG(2, 2, 10, 56), Trans. New York Acad. Sci. 81 (1969), 656675.Google Scholar
6. Goethals, J. M., On the Golay perfect binary code, J. Combinatorial theory (to appear).Google Scholar
7. Goethals, J. M. and Seidel, J. J., Orthogonal matrices with zero diagonal, Can. J. Math. 19 (1967), 10011010.Google Scholar
8. Golay, M., Notes on digital coding, IRE Proc. 87 (1949), 637.Google Scholar
9. Hall, M. Jr., Combinatorial theory (Blaisdell, Waltham, Massachusetts, 1967).Google Scholar
10. Hall, M. Jr., and Swift, J. D., Determination of Steiner triple systems of order 15, Math. Tables Aids Comput. 9 (1955), 146156.Google Scholar
11. Higman, D. G. and Sims, C. C., A simple group of order 44,353,000, Math. Z. 105 (1968), 110113.Google Scholar
12. Hughes, D. R., On t-designs and groups, Amer. J. Math. 87 (1965), 761778.Google Scholar
13. Karlin, M., New binary coding results by circulants, IEEE Trans. Information Theory 15 (1969), 8192.Google Scholar
14. van Lint, J. H. and Seidel, J. J., Equilateral point sets in elliptic geometry, Nederl. Akad. Wetensch. Proc. Ser. A 69 ( = Nederl. Akad. Wetensch. Indag. Math. 28) (1966), 335348.Google Scholar
15. Mesner, D. M., A new family of partially balanced incomplete block designs with some Latin square design properties, Ann. Math. Statist. 88 (1967), 571581.Google Scholar
16. Paige, L. J., A note on the Mathieu groups, Can. J. Math. 9 (1957), 1518.Google Scholar
17. Peterson, W. W., Err or-correcting codes (The M.I.T. Press, Cambridge, 1961.)Google Scholar
18. Ryser, H. J., Combinatorial mathematics, The Carus Mathematical Monographs, No. 14, Published by Math. Assoc. Amer, ((distributed by) Wiley, New York, 1963).Google Scholar
19. Seidel, J. J., Strongly regular graphs ofLi-type and of triangular type, Nederl. Akad. Wetensch. Proc. Ser. A 70 (= Nederl. Akad. Wetensch. Indag. Math. 29) (1967), 188196.Google Scholar
20. Seidel, J. J., Strongly regular graphs with ( — 1, 1, 0) adjacency matrix having eigenvalue 3, Linear Algebra and Appl. 1 (1968), 281298.Google Scholar
21. Seidel, J. J., Strongly regular graphs, Proc. 3rd Waterloo Conference in Combinatorics, pp. 185 198, Recent Progress in Combinatorics, edited by Tutte, W. T. (Academic Press, New York, 1959).Google Scholar
22. Shrikhande, S. S., On the dual of some balanced incomplete block designs, Biometrics 8 (1952), 6672.Google Scholar
23. Stanton, R. G. and Kalbfleisch, J. G., Quasi-symmetric balanced incomplete block designs, J. Combinatorial Theory 4 (1968), 391396.Google Scholar
24. Witt, E., Die 5-fach transitiven Gruppen von Mathieu, Abh. Math. Sem. Hamburg Univ. 12 (1938), 256264.Google Scholar
25. Witt, E., Uber Steinersche Système, Abh. Math. Sem. Hamburg Univ. 12 (1938), 265275.Google Scholar