Preferences Single-Peaked on a Tree: Sampling and Tree Recognition

J. Sliwinski, E. Elkind
IJCAI 2019
Abstract
In voting theory, impossibility results and computational hardness results are often circumvented by recognising that voters' preferences are not arbitrary, but lie within a restricted domain. Uncovering the structure of the underlying domain often provides useful insights about the nature of the alternative space, and may be helpful in identifying a collective choice. Preferences single-peaked on a tree are an example of a relatively broad domain that nonetheless exhibits several desirable properties. We consider the setting where voters' preferences are independently sampled from rankings that are single-peaked on a given tree, and study the problem of reliably identifying the tree that generated the observed votes. We test our algorithm empirically; to this end, we develop an algorithm to uniformly sample preferences that are single-peaked on a given tree.

Experiments:

Election type Culture Candidates Voters Instances Parameters
Ordinal Hand-Crafted [5-127] {?} 2000 None