Interpreting and explaining pagerank through argumentation semantics

Article type: Research Article

Authors: Albini, Emanuele^{a; b; *} | Baroni, Pietro^a | Rago, Antonio^b | Toni, Francesca^b

Affiliations: [a] Dipartimento di Ingegneria dell’Informazione, Università degli Studi di Brescia, 25123 Brescia, Italy | [b] Department of Computing, Imperial College London, South Kensington Campus SW7 2AZ London, UK

Correspondence: [*] Corresponding author: Emanuele Albini. E-mail: [email protected].

Abstract: In this paper we show how re-interpreting PageRank as an argumentation semantics for a bipolar argumentation framework empowers its explainability. After showing that PageRank, naively re-interpreted as an argumentation semantics for support frameworks, fails to satisfy some generally desirable properties, we propose a novel approach able to reconstruct PageRank as a gradual semantics of a suitably defined bipolar argumentation framework, while satisfying these properties. We then show how the theoretical advantages afforded by this approach also enjoy an enhanced explanatory power: we propose several types of argument-based explanations for PageRank, each of which focuses on different aspects of the algorithm and uncovers information useful for the comprehension of its results.

Keywords: PageRank, explainability, gradual argumentation semantics, quantitative bipolar argumentation frameworks

DOI: 10.3233/IA-210095

Journal: Intelligenza Artificiale, vol. 15, no. 1, pp. 17-34, 2021