Which are the True Defeasible Logics?

TL;DR

This paper explores the class of defeasible logics, focusing on the recent logic DL(∂∥), and proposes a broader class that includes this logic while maintaining traditional properties.

Contribution

It introduces a new class of defeasible logics that encompasses DL(∂∥) and preserves key properties of traditional defeasible reasoning.

Findings

DL(∂∥) introduces new features to defeasible logics

A broader class of defeasible logics is defined

Traditional properties are retained in the new class

Abstract

The class of defeasible logics is only vaguely defined -- it is defined by a few exemplars and the general idea of efficient reasoning with defeasible rules. The recent definition of the defeasible logic $DL(\partial_{||})$ introduced new features to such logics, which have repercussions that we explore. In particular, we define a class of logics that accommodates the new logic while retaining the traditional properties of defeasible logics.