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Counterfactuals in Logic Programming with Applications to Morality (NOVA-LINCS Seminar)
{ Wed, 19 Nov 2014, 14h00 }

By: Luis Moniz Pereira  [ show info ] ; Ari Saptawijaya  [ show info ]

*** Joint CENTRIA/CITI/NOVA LINCS seminar ***

Counterfactuals are conjectures about alternatives to events that did not occur in the past; thoughts about what would have happened, had an alternative event occurred. Herein we show how counterfactual reasoning is modeled using Logic Programming (LP), particularly by benefitting from LP abduction and updating. The approach is inspired by Pearl’s causal model of counterfactuals, where causal direction and conditional reasoning are captured by inferential arrows of rules in logic programs. In this approach, LP abduction hypothesizes background conditions from given evidences or observations, whereas LP updating helps frame these background conditions as a counterfactual’s context. Moreover, LP updating imposes causal interventions into the program, imposing minimal adjustments in the model through defeasible LP rules. We apply counterfactuals to computational morality resorting to this LP-based approach, and show their potential for specifying and querying morality issues, viz., to examine viewpoints on moral permissibility of actions through classic moral examples from literature. The results from this application have been validated on a prototype implementing the approach on top of an integrated LP abduction and updating system with tabling.

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