Unchallenged Selection Function

The selection function $\alpha_{\mathsf{uc}}(X,Y,Z) = X \cup Y$ selects only the unattacked and unchallenged initial sets of the current reduct.

Reference

Thimm, M. (2022). Revisiting Initial Sets in Abstract Argumentation. Argument & Computation, 13(3), pp. 325–360.