scholarly journals Minimum embedding of any Steiner triple system into a 3-sun system via matchings

2021 ◽  
Vol 344 (7) ◽  
pp. 112409
Author(s):  
Giovanni Lo Faro ◽  
Antoinette Tripodi
2010 ◽  
Vol 62 (2) ◽  
pp. 355-381 ◽  
Author(s):  
Daniel Král’ ◽  
Edita Máčajov´ ◽  
Attila Pór ◽  
Jean-Sébastien Sereni

AbstractIt is known that a Steiner triple system is projective if and only if it does not contain the four-triple configuration C14. We find three configurations such that a Steiner triple system is affine if and only if it does not contain one of these configurations. Similarly, we characterise Hall triple systems using two forbidden configurations.Our characterisations have several interesting corollaries in the area of edge-colourings of graphs. A cubic graph G is S-edge-colourable for a Steiner triple system S if its edges can be coloured with points of S in such a way that the points assigned to three edges sharing a vertex form a triple in S. Among others, we show that all cubic graphs are S-edge-colourable for every non-projective nonaffine point-transitive Steiner triple system S.


1981 ◽  
Vol 33 (6) ◽  
pp. 1365-1369 ◽  
Author(s):  
K. T. Phelps

A Steiner system S(t, k, v) is a pair (P, B) where P is a v-set and B is a collection of k-subsets of P (usually called blocks) such that every t-subset of P is contained in exactly one block of B. As is well known, associated with each point x ∈ P is a S(t � 1, k � 1, v � 1) defined on the set Px = P\{x} with blocksB(x) = {b\{x}|x ∈ b and b ∈ B}.The Steiner system (Px, B(x)) is said to be derived from (P, B) and is called (obviously) a derived Steiner (t – 1, k – 1)-system. Very little is known about derived Steiner systems despite much effort (cf. [11]). It is not even known whether every Steiner triple system is derived.Steiner systems are closely connected to equational classes of algebras (see [7]) for certain values of k.


2007 ◽  
Vol 06 (01) ◽  
pp. 1-20 ◽  
Author(s):  
MICHAEL K. KINYON ◽  
J. D. PHILLIPS ◽  
PETR VOJTĚCHOVSKÝ

C-loops are loops satisfying the identity x(y · yz) = (xy · y)z. We develop the theory of extensions of C-loops, and characterize all nuclear extensions provided the nucleus is an abelian group. C-loops with central squares have very transparent extensions; they can be built from small blocks arising from the underlying Steiner triple system. Using these extensions, we decide for which abelian groups K and Steiner loops Q there is a nonflexible C-loop C with center K such that C/K is isomorphic to Q. We discuss possible orders of associators in C-loops. Finally, we show that the loops of signed basis elements in the standard real Cayley–Dickson algebras are C-loops.


Author(s):  
Alan R. Prince

SynopsisA standard method of constructing Steiner triple systems of order 19 from the Steiner triple system of order 9 gives rise to 212 different such systems. It is shown that there are just three isomorphism classes amongst these systems. Representatives of each isomorphism class are described and the orders of their automorphism groups are determined.


2014 ◽  
Vol 513-517 ◽  
pp. 3061-3064
Author(s):  
Xiao Yi Li ◽  
Zhao Di Xu ◽  
Wan Xi Chou

This paper describes the basic concept of constructing Steiner triple system of order and gives the definition edge matrix of a complete graph. It proposes a method of constructing Steiner triple system of order. The entire procedure of constructing Steiner triple system of order .It discusses the enumeration problem of Steiner triple system.


2007 ◽  
Vol 4 (8) ◽  
pp. 659-664 ◽  
Author(s):  
Vanessa Vermeirssen ◽  
Bart Deplancke ◽  
M Inmaculada Barrasa ◽  
John S Reece-Hoyes ◽  
H Efsun Arda ◽  
...  

1974 ◽  
Vol 26 (1) ◽  
pp. 225-232 ◽  
Author(s):  
Charles C. Lindner

A Steiner triple system is a pair (Q, t) where Q is a set and t a collection of three element subsets of Q such that each pair of elements of Q belong to exactly one triple of t. The number |Q| is called the order of the Steiner triple system (Q, t). It is well-known that there is a Steiner triple system of order n if and only if n ≡ 1 or 3 (mod 6). Therefore in saying that a certain property concerning Steiner triple systems is true for all n it is understood that n ≡ 1 or 3 (mod 6). Two Steiner triple systems (Q, t1) and (Q, t2) are said to be disjoint provided that t1 ∩ t2 = Ø. Recently, Jean Doyen has shown the existence of a pair of disjoint Steiner triple systems of order n for every n ≧ 7 [1].


2006 ◽  
Vol 85 (1-2) ◽  
pp. 90-109 ◽  
Author(s):  
Małgorzata Prażmowska ◽  
Krzysztof Prażmowski

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