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argumentation-bipolar

The argumentation-bipolar crate extends Dung's attack-only model with a second directed edge relation: support. It implements necessary support semantics (Cayrol & Lagasquie-Schiex 2005, Nouioua & Risch 2011): if A supports B, then A must be accepted for B to be acceptable. The crate builds on top of argumentation's Dung semantics by flattening bipolar frameworks — computing the closed attack relation and filtering extensions that are not support-closed — and provides SCC-based coalition detection over the support graph.

Crate: argumentation-bipolar (crates.io · rustdoc)

Key types​

BipolarFramework<A>​

A bipolar argumentation framework generic over argument type A. Stores arguments and two independent directed edge sets (attacks and supports). Self-support is rejected; self-attack is allowed (matches the core crate's convention). Provides add_attack, add_support, remove_support, direct_attackers, direct_supporters, and supporter_map. → Full docs

Coalition<A>​

A strongly-connected component of the support graph — a group of arguments that mutually support each other. Returned by detect_coalitions. → Full docs

EdgeKind​

Discriminates attack edges from support edges. Used in derived-relation and flatten queries. → Full docs

CoalitionId​

An opaque identifier for a detected coalition, stable for the lifetime of a detect_coalitions call. → Full docs

Key functions / methods​

FunctionReturnsWhat it does
detect_coalitions(&bf)Vec<Coalition<A>>Runs Tarjan SCC on the support graph to find mutually-supporting groups.
bipolar_preferred_extensions(&bf)Result<Vec<HashSet<A>>>Computes preferred extensions under necessary-support semantics: flattens the closed attack relation, runs Dung preferred semantics, then filters non-support-closed extensions.
bipolar_grounded_extension(&bf)Result<HashSet<A>>Computes the grounded extension of the flattened framework, then removes arguments whose necessary supporters are absent.
bipolar_stable_extensions(&bf)Result<Vec<HashSet<A>>>Stable extensions of the flattened framework, filtered for support-closure.
bipolar_complete_extensions(&bf)Result<Vec<HashSet<A>>>Complete extensions of the flattened framework, filtered for support-closure.
is_support_closed(ext, bf)boolReturns true iff every argument in ext has all its necessary supporters also in ext.
derived::closed_attacks(&bf)HashSet<(A, A)>Computes the full closed attack relation (direct + supported + secondary + mediated) per C&LS 2005 §3.
flatten::flatten(&bf)ArgumentationFramework<A>Produces an equivalent plain Dung AF whose edges are the closed attack relation.

Errors​

Error::ArgumentNotFound(String)​

An operation referenced an argument not in the framework.

Error::IllegalSelfSupport(String)​

add_support was called with identical supporter and supported arguments. Self-support is not valid under necessary-support semantics.

Error::Dung(argumentation::Error)​

An error propagated from the underlying Dung layer (e.g., framework too large for subset enumeration).

See also​