Assumption-Based Argumentation with Preferences.

This website ( carries the interface of ABAplus ( Z. Bao, K. Čyras, F. Toni – ABAplus: Attack Reversal in Abstract and Structured Argumentation with Preferences), a system that implements reasoning with the computational argumentation formalism ABA⁺ ( K. Čyras, F. Toni – ABA⁺: Assumption-Based Argumentation with Preferences). ABA⁺ is a novel approach to handling preferences in structured argumentation. It extends the well established structured argumentation formalism Assumption-Based Argumentation (ABA) with a binary preference relation over assumptions. The preferences are incorporated directly into the attack relation to reverse attacks.

On this website, the users can specify the individual components of an ABA⁺ framework (i.e. rules, assumptions with their contraries, and preferences among assumptions). The system then visualizes the ABA⁺ framework, computes extensions (under various semantics) and their conclusions, at the same time allowing for a comparison between extensions.

    In ABAplus, an ABA⁺ framework is specified as follows:
  • myAsm(a). specifies that a is an assumption;
  • contrary(a, x). specifies that x is the contrary of assumption a;
  • myRule(h, [b1, …, bn]). specifies that h <- b1, …, bn is a rule;
  • myPrefLT(b, a). specifies that assumption a is strictly preferred over assumption b;
  • myPrefLE(b, a). specifies that assumption a is strictly or equally preferred over assumption b.

Either choose a file (with extension .pl) containing the specification of an ABA⁺ framework and UPLOAD

Or input an ABA⁺ framework in the box below and LOAD:

For more information about ABA⁺ and/or to report any issues with/bugs of the system please contact Kristijonas Čyras ( or Francesca Toni ( The implementation has been carried out by Ziyi Bao (, under the Undergraduate Research Opportunities Programme (UROP,, supervised by K. Čyras and F. Toni.