Hi,
please note that the following technical report is available on http://aib.informatik.rwth-aachen.de:
Achim Blumensath: Axiomatising Tree-interpretable Structures 2001-10
Abstract: We introduce the class of tree-interpretable structures which generalises the notion of a prefix-recognisable graph to arbitrary relational structures. We prove that every tree-interpretable structure is finitely axiomatisable in guarded second-order logic with cardinality quantifiers.
Note: This is an extended version of the corresponding STACS'02 paper.
Best regards,
Martin Leucker
tr-announce@lists.rwth-aachen.de