  Transitive proxy voting (or "liquid democracy") is a novel form of collective
decision making, often framed as an attractive hybrid of direct and
representative democracy. Although the ideas behind liquid democracy have
garnered widespread support, there have been relatively few attempts to model
it formally. This paper makes three main contributions. First, it proposes a
new social choice-theoretic model of liquid democracy, which is distinguished
by taking a richer formal perspective on the process by which a voter chooses a
proxy. Second, it examines the model from an axiomatic perspective, proving (a)
a proxy vote analogue of May's Theorem and (b) an impossibility result
concerning monotonicity properties in a proxy vote setting. Third, it explores
the topic of manipulation in transitive proxy votes. Two forms of manipulation
specific to the proxy vote setting are defined, and it is shown that
manipulation occurs in strictly more cases in proxy votes than in classical
votes.
