© 1996 by London Mathematical Society
© The London Mathematical Society
Splitting of Finite Covers of
0-Categorical Structures
School of Mathematics, University of East Anglia Norwich NR4 7TJ E-mail: D.Evans{at}uea.ac.uk
Received 14 September 1993. Revision received 27 February 1995.
Suppose that W is a countable
0-categorical structure. We investigate the question as to whether every finite cover of W splits, that is, has an expansion which is a trivial finite cover of W. We show that for most primitive structures W which are homogeneous for a single binary relation (homogeneous graphs, partial orderings, the Henson digraphs, ...) any finite cover splits. However, in contrast to this, we show that there are non-split covers (with finite kernels) of the countable, universal, homogeneous local order.