A lemma in open sequential voting by veto

The paper is devoted to the investigation of intuitively rational choice in a hierarchical game that is a model of election by open sequential veto-voting. Casting a veto against voter's least preferred alternative (among remaining ones) may not lead to a sophisticated equilibrium. It means that sincere choice (being intuitive) is not rational. There arises the problem of finding conditions under which a sophisticated optimal sequence of actions is intuitively rational. We prove that in the case of strict preference ordering of alternatives, there exists an intuitively rational sophisticated optimal sequence. In the sequence, each voter vetoes an alternative less preferred than the sophisticated equilibrium outcome. Thus, only intuitively rational strategies are to be considered, although complete information about voters' preferences is still needed.