# Defense semantics of argumentation: encoding reasons for accepting arguments

## TL;DR

This paper introduces a novel defense semantics for argumentation graphs, encoding reasons for accepting arguments and proposing new notions of defense, equivalence, and summarization methods based on these semantics.

## Contribution

It presents a new defense semantics, defense graphs, and introduces root and direct reasons for argument acceptance, advancing argumentation theory.

## Key findings

- Defines defense semantics and defense graphs.
- Introduces root and direct reasons for acceptance.
- Proposes root equivalence for argument graphs.

## Abstract

In this paper we show how the defense relation among abstract arguments can be used to encode the reasons for accepting arguments. After introducing a novel notion of defenses and defense graphs, we propose a defense semantics together with a new notion of defense equivalence of argument graphs, and compare defense equivalence with standard equivalence and strong equivalence, respectively. Then, based on defense semantics, we define two kinds of reasons for accepting arguments, i.e., direct reasons and root reasons, and a notion of root equivalence of argument graphs. Finally, we show how the notion of root equivalence can be used in argumentation summarization.