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Tutorial: Nonmonotonic Logics

Table of Contents

Course Description

The tutorial takes place in the context of the TRS Reasoning School of NAT@Logic2015 in Natal, Brazil.

Defeasible reasoning is indispensable when dealing with a world full of uncertainties: we constantly draw conclusions that we may reject later in view of new information. For instance, when noticing that the streets are wet, I infer that it has been raining. However, once I discern that the roofs are not wet, I retract my previous inference. In situations like this, we make inferences from premises that do not warrant that our conclusions holds: they only warrant that the a conclusion is sufficiently likely. Defeasible reasoning is not restricted to everyday contexts. It is also abundant in the (pure and applied) sciences and in expert reasoning. E.g., when diagnosing a patient, John, who shows signs that best fit hyperthyroidism, a physician may conclude that John should be tested further for this condition. However, as soon as our physician is informed that John's thyroid has been removed, she will retract her previous inference. As these examples indicate, defeasible reasoning comes in many forms: we reason from effect to cause (abduction), we make generalizations (induction), we reason on the basis of what is normally or typically the case (default reasoning), we infer on grounds of the information our senses give us about our environment, etc. In order to explicate and evaluate such reasoning processes, formal methods were developed: nonmonotonic logics. In this tutorial we will discuss some central approaches in nonmonotonic logic.


  • Session 1: [2015-09-02 Wed 19:20]–[2015-09-02 Wed 20:50]
  • Session 2: [2015-09-03 Thu 19:20]–[2015-09-03 Thu 20:50]


Day 1


Day 2


Author: christian

Created: 2015-09-03 Thu 15:44