70views more  JSC 2010»
13 years 1 months ago
Liouvillian solutions of linear difference-differential equations
For a field k with an automorphism and a derivation , we introduce the notion of liouvillian solutions of linear difference-differential systems {(Y ) = AY, (Y ) = BY } over k an...
Ruyong Feng, Michael F. Singer, Min Wu
122views more  IJAC 2010»
13 years 5 months ago
Automorphic orbits in Free Groups: Words versus Subgroups
We show that the following problems are decidable in rank 2 free groups: does a given finitely generated subgroup H contain primitive elements? and does H meet the automorphic or...
Pedro V. Silva, Pascal Weil
58views more  MOC 2002»
13 years 6 months ago
Kirkman triple systems of order 21 with nontrivial automorphism group
There are 50,024 Kirkman triple systems of order 21 admitting an automorphism of order 2. There are 13,280 Kirkman triple systems of order 21 admitting an automorphism of order 3. ...
Myra B. Cohen, Charles J. Colbourn, Lee A. Ives, A...
72views more  APAL 1999»
13 years 6 months ago
Lattices of Modal Logics and Their Groups of Automorphisms
The present paper investigates the groups of automorphisms for some lattices of modal logics. The main results are the following. The lattice of normal extensions of S4.3, NExt S4....
Marcus Kracht
54views more  CPC 2000»
13 years 7 months ago
Involutions Of Connected Binary Matroids
We prove that if an involution is an automorphism of a connected binary matroid M, then there is a hyperplane of M that is invariant under . We also consider extensions of this re...
Joseph E. Bonin
121views more  COMBINATORICS 2006»
13 years 7 months ago
Identifying Graph Automorphisms Using Determining Sets
A set of vertices S is a determining set for a graph G if every automorphism of G is uniquely determined by its action on S. The determining number of a graph is the size of a sma...
Debra L. Boutin
147views System Software» more  CC 2006»
13 years 7 months ago
Complexity of Ring Morphism Problems
Abstract. We study the complexity of the isomorphism and automorphism problems for finite rings. We show that both integer factorization and graph isomorphism reduce to the problem...
Neeraj Kayal, Nitin Saxena
94views more  DM 2010»
13 years 7 months ago
Hypermap operations of finite order
Abstract: Duality and chirality are examples of operations of order 2 on hypermaps. James showed that the groups of all operations on hypermaps and on oriented hypermaps can be ide...
Gareth A. Jones, Daniel Pinto