Perspectives: A Declarative Bias Mechanism
for Case Retrieval *

Josep Llus Arcos and Ramon Lpez de Mntaras


IIIA, Artificial Intelligence Research Institute
CSIC, Spanish Council for Scientific Research
Campus UAB, 08193 Bellaterra, Catalonia, Spain.
{arcos ,mantaras}@iiia.csic.es



Abstract. The aim of this paper is to present a mechanism, called perspectives, 
to describe declarative biases for case retrieval in structured
representations of cases. Our approach is based on the observation that,
in complex tasks, the identification of the relevant aspects for retrieval
in a given situation may involve the use of knowledge intensive methods.
This identification process requires dynamical decisions about the relevant 
aspects of a problem and usually forces to consider non predefined
retrieval indexes in the memory of cases. Declarative biases provide a
flexible way of constructing dynamical perspectives for retrieval in the
memory of cases. We have implemented the notion of perspectives in a
reflective object-centered representation language, called Noos, based on
feature terms. Finally, we have used perspectives as declarative biases for
retrieval in the Saxex application, a complex real-world case-based reasoning 
system for generating expressive performances of melodies based
on examples of human performances that are represented as structured
cases.
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