Magic letter groups

2007 ◽  
Vol 91 (522) ◽  
pp. 493-499
Author(s):  
Mike Pearson ◽  
Ian Short
Keyword(s):  
Permutation Group ◽  
Isomorphism Type ◽  
Permutation Groups ◽  
Natural Manner ◽  
Finite Permutation Group

Certain numeric puzzles, known as ‘magic letters’, each have a finite permutation group associated with them in a natural manner. We describe how the isomorphism type of these permutation groups relates to the structure of the magic letters.

scholarly journals ON THE HEIGHT AND RELATIONAL COMPLEXITY OF A FINITE PERMUTATION GROUP

2021 ◽  
pp. 1-40
Author(s):  
NICK GILL ◽  
BIANCA LODÀ ◽  
PABLO SPIGA
Keyword(s):  
Permutation Group ◽  
Model Theory ◽  
Independent Set ◽  
Maximum Size ◽  
Proper Subset ◽  
Permutation Groups ◽  
Finite Permutation Group ◽  
Pointwise Stabilizer ◽  
Relational Complexity

Abstract Let G be a permutation group on a set $\Omega $ of size t. We say that $\Lambda \subseteq \Omega $ is an independent set if its pointwise stabilizer is not equal to the pointwise stabilizer of any proper subset of $\Lambda $ . We define the height of G to be the maximum size of an independent set, and we denote this quantity $\textrm{H}(G)$ . In this paper, we study $\textrm{H}(G)$ for the case when G is primitive. Our main result asserts that either $\textrm{H}(G)< 9\log t$ or else G is in a particular well-studied family (the primitive large–base groups). An immediate corollary of this result is a characterization of primitive permutation groups with large relational complexity, the latter quantity being a statistic introduced by Cherlin in his study of the model theory of permutation groups. We also study $\textrm{I}(G)$ , the maximum length of an irredundant base of G, in which case we prove that if G is primitive, then either $\textrm{I}(G)<7\log t$ or else, again, G is in a particular family (which includes the primitive large–base groups as well as some others).

On the Group of a Directed Graph

1966 ◽  
Vol 18 ◽  
pp. 211-220 ◽  
Author(s):  
Robert L. Hemminger
Keyword(s):  
Finite Group ◽  
Permutation Group ◽  
Directed Graph ◽  
Directed Graphs ◽  
Symmetric Case ◽  
Related Question ◽  
Permutation Groups ◽  
Symmetric Graph ◽  
Finite Permutation Group ◽  
Symmetric Graphs

In 1938, Frucht (2) proved that for any given finite group G there exists a finite symmetric graph X such that G(X) is abstractly isomorphic to G. Since G(X) is a permutation group, it is natural to ask the following related question : If P is a given finite permutation group, does there exist a symmetric (and more generally a directed) graph X such that G(X) and P are isomorphic (see Convention below) as permutation groups? The answer for the symmetric case is negative as seen in (3) and more recently in (1). It is the purpose of this paper to deal with this problem further, especially in the directed case. In §3, we supplement Kagno's results (3, pp. 516-520) for symmetric graphs by giving the corresponding results for directed graphs.

scholarly journals Quotients of permutation groups

1998 ◽  
Vol 57 (3) ◽  
pp. 493-495
Author(s):  
John Cossey
Keyword(s):  
Normal Subgroup ◽  
Permutation Group ◽  
Faithful Representation ◽  
Permutation Representation ◽  
Permutation Groups ◽  
Fitting Subgroup ◽  
Finite Permutation Group ◽  
Special Cases

If G is a finite permutation group of degree d and N is a normal subgroup of G, Derek Holt has given conditions which show that in some important special cases the least degree of a faithful permutation representation of the quotient G/N will be no larger than d. His conditions do not apply in all cases of interest and he remarks that it would be interesting to know if G/F(G) has a faithful representation of degree no larger than d (where F(G) is the Fitting subgroup of G). We prove in this note that this is the case.

scholarly journals On multiply transitive permutation groups

1978 ◽  
Vol 26 (1) ◽  
pp. 57-58
Author(s):  
G. P. Monro ◽  
D. E. Taylor
Keyword(s):  
Permutation Group ◽  
Subject Classification ◽  
Permutation Groups ◽  
Combinatorial Proof ◽  
Bell Numbers ◽  
Finite Permutation Group ◽  
Multiply Transitive

AbstractWe present a direct combinatorial proof of the characterization of the degree of transivity of a finite permutation group in terms of the Bell numbers.Subject classification (Amer. Math.Soc. (MOS) 1970): 20 B 20.

scholarly journals Transversals in permutation groups and factorisations of complete graphs

2002 ◽  
Vol 65 (2) ◽  
pp. 277-288 ◽  
Author(s):  
Gil Kaplan ◽  
Arieh Lev
Keyword(s):  
Permutation Group ◽  
Directed Graph ◽  
Sufficient Conditions ◽  
Combinatorial Problems ◽  
Permutation Groups ◽  
Transitive Permutation Group ◽  
Complete Graphs ◽  
Frobenius Theorem ◽  
Disjoint Cycles ◽  
Finite Set

Let G be a transitive permutation group acting on a finite set of order n. We discuss certain types of transversals for a point stabiliser A in G: free transversals and global transversals. We give sufficient conditions for the existence of such transversals, and show the connection between these transversals and combinatorial problems of decomposing the complete directed graph into edge disjoint cycles. In particular, we classify all the inner-transitive Oberwolfach factorisations of the complete directed graph. We mention also a connection to Frobenius theorem.

scholarly journals Enumerating Finite Racks, Quandles and Kei

10.37236/3262 ◽  
2013 ◽  
Vol 20 (3) ◽  
Author(s):  
Simon R. Blackburn
Keyword(s):  
Permutation Group ◽  
Lower Bounds ◽  
Binary Operation ◽  
Independent Interest ◽  
Upper And Lower Bounds ◽  
Permutation Groups ◽  
Isomorphism Classes ◽  
Operator Group ◽  
The Relationship

A rack of order $n$ is a binary operation $\vartriangleright$ on a set $X$ of cardinality $n$, such that right multiplication is an automorphism. More precisely, $(X,\vartriangleright)$ is a rack provided that the map $x\mapsto x\vartriangleright y$ is a bijection for all $y\in X$, and $(x\vartriangleright y)\vartriangleright z=(x\vartriangleright z)\vartriangleright (y\vartriangleright z)$ for all $x,y,z\in X$.The paper provides upper and lower bounds of the form $2^{cn^2}$ on the number of isomorphism classes of racks of order $n$. Similar results on the number of isomorphism classes of quandles and kei are obtained. The results of the paper are established by first showing how an arbitrary rack is related to its operator group (the permutation group on $X$ generated by the maps $x\mapsto x\vartriangleright y$ for $y\in Y$), and then applying some of the theory of permutation groups. The relationship between a rack and its operator group extends results of Joyce and of Ryder; this relationship might be of independent interest.

Permutation groups and orbits on the power set

2019 ◽  
Vol 19 (12) ◽  
pp. 2150005
Author(s):  
Yong Yang
Keyword(s):  
Permutation Group ◽  
Permutation Groups ◽  
Power Set ◽  
Composition Factors

Let [Formula: see text] be a permutation group of degree [Formula: see text] and let [Formula: see text] denote the number of set-orbits of [Formula: see text]. We determine [Formula: see text] over all groups [Formula: see text] that satisfy certain restrictions on composition factors.

scholarly journals EMBEDDING PERMUTATION GROUPS INTO WREATH PRODUCTS IN PRODUCT ACTION

2012 ◽  
Vol 92 (1) ◽  
pp. 127-136 ◽  
Author(s):  
CHERYL E. PRAEGER ◽  
CSABA SCHNEIDER
Keyword(s):  
Permutation Group ◽  
Wreath Product ◽  
Automorphism Groups ◽  
Wreath Products ◽  
Error Correcting Codes ◽  
Permutation Groups ◽  
Graph Products ◽  
Product Action ◽  
Hamming Graphs

AbstractWe consider the wreath product of two permutation groups G≤Sym Γ and H≤Sym Δ as a permutation group acting on the set Π of functions from Δ to Γ. Such groups play an important role in the O’Nan–Scott theory of permutation groups and they also arise as automorphism groups of graph products and codes. Let X be a subgroup of Sym Γ≀Sym Δ. Our main result is that, in a suitable conjugate of X, the subgroup of SymΓ induced by a stabiliser of a coordinate δ∈Δ only depends on the orbit of δ under the induced action of X on Δ. Hence, if X is transitive on Δ, then X can be embedded into the wreath product of the permutation group induced by the stabiliser Xδ on Γ and the permutation group induced by X on Δ. We use this result to describe the case where X is intransitive on Δ and offer an application to error-correcting codes in Hamming graphs.

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