Robustness of Greedy Approval Rules

We study the robustness of GreedyCC, GreedyPAV, and Phragmén’s sequential rule, using framework introduced by Bredereck et al. [6] for case (multiwinner) ordinal elections adopted to approval setting Gawron Faliszewski [15]. First, we show that each our rules every committee size k, there are in which adding or removing a certain causes winning completely change (i.e., after operation is disjoint from one before operation). Second, problem deciding how many approvals need be added (or removed) an election its outcome $${{\textrm{NP}}}$$ -complete rules. Finally, experimentally evaluate presence random noise.