  In this paper we present the first step in a larger series of experiments for
the induction of predicate/argument structures. The structures that we are
inducing are very similar to the conceptual structures that are used in Frame
Semantics (such as FrameNet). Those structures are called messages and they
were previously used in the context of a multi-document summarization system of
evolving events. The series of experiments that we are proposing are
essentially composed from two stages. In the first stage we are trying to
extract a representative vocabulary of words. This vocabulary is later used in
the second stage, during which we apply to it various clustering approaches in
order to identify the clusters of predicates and arguments--or frames and
semantic roles, to use the jargon of Frame Semantics. This paper presents in
detail and evaluates the first stage.
