Function closed_attacks 

pub fn closed_attacks<A>(framework: &BipolarFramework<A>) -> HashSet<(A, A)>
where
    A: Clone + Eq + Hash,

Compute the closed attack set for a bipolar framework under necessary-support semantics.

The returned set contains (attacker, target) pairs for every direct attack plus every derived attack produced by the supported and secondary/mediated rules. Self-attacks are preserved from the direct set (Dung allows them) but are not introduced by derivation.

The closure is deterministic and order-independent.