JR Scally/ Jon Matthis Grad Student Presentations


JR Scally/ Jon Matthis Grad Student Presentations

Sage 4101

November 17, 2010 12:00 PM - 2:00 PM

JR Scally: Title:  "The (Real) World is Not Enough"

Abstract:   A critical component of human cognition is the ability to reason in domains other than the "real" world of direct perception and concrete experience. This ability is key to imagination, learning from mistakes, reasoning about the beliefs of others, and the novel blending of concepts. While reasoning about realistic possibilities does not present large challenges for a simulation approach, reasoning about counterfactual situations presents a number of problems which have been explored at great length in philosophy, psychology, and linguistics. Our approach focuses on the computational challenges of real time reasoning over worlds which are built on counterfactual assumptions. In this talk, I will present the problem of tractable counterfactual reasoning as an aspect of the Implied Matching Problem, and demonstrate new features of the Polyscheme architecture which enable counterfactual reasoning through dynamic belief revision, inheritance between worlds, and lazy instantiation of overrides. These features will be demonstrated in several Polyscheme models which display counterfactual reasoning in a variety of scenarios and  show that reasoning over counterfactual worlds can unify many aspects of knowledge representation, and that an approach built on inheritance and lazy resolution of conflicts leads to more compact models and more scalable run times.

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