 If a candidate \(X\) is in the set of candidates selected by  a voter, we say that the voter approves of candidate \(X\).  Then, the approval winner is the  candidate with the most approvals. Approval voting has been extensively discussed by Steven Brams and Peter Fishburn (Brams and Fishburn 2007; Brams 2008). See, also, the recent collection of articles devoted to approval voting (Laslier and Sanver 2010). 