Supporting changes in structure in causal model construction

Authors:

Tsai-Ching Lu and Marek J. Druzdzel
Decision Systems Laboratory
School of Information Sciences
and Intelligent Systems Program
University of Pittsburgh
135 North Bellefield Avenue
Pittsburgh, PA 15260, U.S.A.
e-mail: tclu@sis.pitt.edu, marek@sis.pitt.edu

Abstract:

The term "changes in structure," originating from work in econometrics, refers to structural modications invoked by actions on a causal model. In this paper we formalize the representation of reversibility of a mechanism in order to support modeling of changes in structure in systems that contain reversible mechanisms. Causal models built on our formalization can answer two new types of queries: (1) When manipulating a causal model (i.e., making an endogenous variable exogenous), which mechanisms are possibly invalidated and can be removed from the model? (2) Which variables may be manipulated in order to invalidate and, erec- tively, remove a mechanism from a model?