The structure of certain triple systems
Author:
Raphael M. Robinson
Journal:
Math. Comp. 29 (1975), 223241
MSC:
Primary 05B05
MathSciNet review:
0384566
Fulltext PDF Free Access
Abstract 
References 
Similar Articles 
Additional Information
Abstract: For each prime power , there is a triple system of order q whose automorphism group is transitive on unordered pairs. The object of this paper is to study these systems. This is done by analyzing how pairs of elements are linked. The linkage of a and b consists of a triple (a, b, c) and of some cycles in which adjacent pairs of elements form triples alternately with a and with b. Because of the transitivity, the lengths of the cycles will be independent of the choice of a and b. Using a computer, the linkage between two elements was determined for each . Some curious facts concerning the lengths of the cycles were uncovered; for example, the number of cycles of length greater than 4 is even. The systems of prime order were found to have no proper subsystems of order greater than 3. In the remaining case, , there are subsystems of orders 7 and 49, and all subsystems of the same order are isomorphic. For no q with is the automorphism group doubly transitive. Finally, some general results are proved. The cycles of lengths 4 and 6 are determined. Using this result, it is shown that there can be no subsystem of order 7 or 9, except for the subsystems of order 7 when q is a power of 7. Hence, by a theorem of Marshall Hall, the automorphism group cannot be doubly transitive, except possibly when q is a power of 7. (Added August 1974. In a postscript, it is shown that the automorphism group is not doubly transitive in this case either.)
 [1]
Robert
D. Carmichael, Introduction to the theory of groups of finite
order, Dover Publications Inc., New York, 1956. MR 0075938
(17,823a)
 [2]
F. N. COLE, LOUISE D. CUMMINGS & H. S. WHITE, "The complete enumeration of triad systems in 15 elements," Proc. Nat. Acad. Sci. U. S. A., v. 3, 1917, pp. 197199.
 [3]
P.
Dembowski, Finite geometries, Ergebnisse der Mathematik und
ihrer Grenzgebiete, Band 44, SpringerVerlag, Berlin, 1968. MR 0233275
(38 #1597)
 [4]
Marshall
Hall Jr., Automorphisms of Steiner triple systems, IBM J. Res.
Develop 4 (1960), 460–472. MR 0123961
(23 #A1282)
 [5]
Marshall
Hall Jr., Combinatorial theory, Blaisdell Publishing Co. Ginn
and Co., Waltham, Mass.Toronto, Ont.London, 1967. MR 0224481
(37 #80)
 [6]
Marshall
Hall Jr. and J.
D. Swift, Determination of Steiner triple
systems of order 15, Math. Tables Aids
Comput. 9 (1955),
146–152. MR 0080104
(18,192d), http://dx.doi.org/10.1090/S00255718195500801047
 [7]
William
M. Kantor, Automorphism groups of designs, Math. Z.
109 (1969), 246–252. MR 0274306
(43 #71)
 [8]
Heinz
Lüneburg, Steinersche Tripelsysteme mit fahnentransitiver
Kollineationsgruppe., Math. Ann. 149 (1962/1963),
261–270 (German). MR 0145402
(26 #2933)
 [9]
Eugen
Netto, Zur Theorie der Tripelsysteme, Math. Ann.
42 (1893), no. 1, 143–152 (German). MR
1510770, http://dx.doi.org/10.1007/BF01443448
 [10]
Eugen
Netto, Lehrbuch der Combinatorik, Chelsea Publishing Company,
New York, 1958 (German). MR 0095126
(20 #1632)
 [11]
M. REISS, "Ueber eine Steinersche combinatorische Aufgabe," J. Reine Angew. Math., v. 56, 1859, pp. 326344.
 [12]
H. S. WHITE, F. N. COLE & LOUISE D. CUMMINGS, "Complete classification of the triad systems on fifteen elements," Mem. Nat. Acad. Sci. U. S. A., v. 14, no. 2, 1919, 89 pp.
 [1]
 ROBERT D. CARMICHAEL, Introduction to the Theory of Groups of Finite Order, Ginn, Boston, 1937; reprinted, Dover, New York, 1956. MR 17, 823. MR 0075938 (17:823a)
 [2]
 F. N. COLE, LOUISE D. CUMMINGS & H. S. WHITE, "The complete enumeration of triad systems in 15 elements," Proc. Nat. Acad. Sci. U. S. A., v. 3, 1917, pp. 197199.
 [3]
 P. DEMBOWSKI, Finite Geometries, Ergebnisse der Mathematik und ihrer Grenzgebiete, Band 44, SpringerVerlag, Berlin and New York, 1968. MR 38 #1597. MR 0233275 (38:1597)
 [4]
 MARSHALL HALL, JR., "Automorphisms of Steiner triple systems," IBM J. Res. Develop., v. 4, 1960, pp. 460472. MR 23 #A1282. MR 0123961 (23:A1282)
 [5]
 MARSHALL HALL, JR., Combinatorial Theory, Blaisdell, Waltham, Mass., 1967. MR 37 #80. MR 0224481 (37:80)
 [6]
 MARSHALL HALL, JR. & J. D. SWIFT, "Determination of Steiner triple systems of order 15," Math. Tables Aids Comput., v. 9, 1955, pp. 146152. MR 18, 192. MR 0080104 (18:192d)
 [7]
 WILLIAM M. KANTOR, "Automorphism groups of designs," Math. Z., v. 109, 1969, pp. 246252. MR 43 #71. MR 0274306 (43:71)
 [8]
 HEINZ LÜNEBURG, "Steinersche Tripelsysteme mit fahnentransitiver Kollineationsgruppe," Math. Ann., v. 149, 1962/63, pp. 261270. MR 26 #2933. MR 0145402 (26:2933)
 [9]
 EUGEN NETTO, "Zur Theorie der Tripelsysteme," Math. Ann., v. 42. 1893, pp. 143152. MR 1510770
 [10]
 EUGEN NETTO, Lehrbuch der Combinatorik, 2nd ed., Teubner, Leipzig, 1927; reprinted, Chelsea, New York, 1958. MR 20 #1632. MR 0095126 (20:1632)
 [11]
 M. REISS, "Ueber eine Steinersche combinatorische Aufgabe," J. Reine Angew. Math., v. 56, 1859, pp. 326344.
 [12]
 H. S. WHITE, F. N. COLE & LOUISE D. CUMMINGS, "Complete classification of the triad systems on fifteen elements," Mem. Nat. Acad. Sci. U. S. A., v. 14, no. 2, 1919, 89 pp.
Similar Articles
Retrieve articles in Mathematics of Computation
with MSC:
05B05
Retrieve articles in all journals
with MSC:
05B05
Additional Information
DOI:
http://dx.doi.org/10.1090/S0025571819750384566X
PII:
S 00255718(1975)0384566X
Article copyright:
© Copyright 1975 American Mathematical Society
