Dung's semantics satisfy attack removal monotonicity

TL;DR

This paper proves that several semantics in argumentation theory maintain their acceptance status of arguments when attacks are removed, ensuring stability in argument evaluation.

Contribution

It demonstrates that preferred, stable, complete, and grounded semantics satisfy attack removal monotonicity, a property not previously established for these semantics.

Findings

Preferred, stable, complete, and grounded semantics satisfy attack removal monotonicity.

Removing an attack cannot worsen the acceptance status of an argument.

Acceptance statuses are preserved or improved when attacks are removed.

Abstract

We show that preferred, stable, complete, and grounded semantics satisfy attack removal monotonicity. This means that if an attack from b to a is removed, the status of a cannot worsen, e.g. if a was skeptically accepted, it cannot become rejected.