JSC

2010

13 years 1 months ago
2010

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...

IJAC

2010

13 years 5 months ago
2010

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...

MOC

2002

13 years 6 months ago
2002

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. ...

APAL

1999

13 years 6 months ago
1999

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....

CPC

2000

13 years 7 months ago
2000

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...

COMBINATORICS

2006

13 years 7 months ago
2006

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...

CC

2006

Springer

13 years 7 months ago
2006

Springer

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...

DM

2010

13 years 7 months ago
2010

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...