14 research outputs found
Base Size Sets and Determining Sets
Bridging the work of Cameron, Harary, and others, we examine the base size
set B(G) and determining set D(G) of several families of groups. The base size
set is the set of base sizes of all faithful actions of the group G on finite
sets. The determining set is the subset of B(G) obtained by restricting the
actions of G to automorphism groups of finite graphs. We show that for finite
abelian groups, B(G)=D(G)={1,2,...,k} where k is the number of elementary
divisors of G. We then characterize B(G) and D(G) for dihedral groups of the
form D_{p^k} and D_{2p^k}. Finally, we prove B(G) is not equal to D(G) for
dihedral groups of the form D_{pq} where p and q are distinct odd primes.Comment: 10 pages, 1 figur
Fixing Numbers of Graphs and Groups
The fixing number of a graph G is the smallest cardinality of a set of vertices S such that only the trivial automorphism of G fixes every vertex in S. The fixing set of a group Γ is the set of all fixing numbers of finite graphs with automorphism group Γ. Several authors have studied the distinguishing number of a graph, the smallest number of labels needed to label G so that the automorphism group of the labeled graph is trivial. The fixing number can be thought of as a variation of the distinguishing number in which every label may be used only once, and not every vertex need be labeled. We characterize the fixing sets of finite abelian groups, and investigate the fixing sets of symmetric groups
Critical Pebbling Numbers of Graphs
We define three new pebbling parameters of a connected graph , the -,
-, and -critical pebbling numbers. Together with the pebbling number, the
optimal pebbling number, the number of vertices and the diameter of the
graph, this yields 7 graph parameters. We determine the relationships between
these parameters. We investigate properties of the -critical pebbling
number, and distinguish between greedy graphs, thrifty graphs, and graphs for
which the -critical pebbling number is .Comment: 26 page