A parameterized characterization of height-based total extensions of Principal filtral opportunity rankings is provided and shown to include as a special case a version of the well-known Pattanaik-Xu characterization of the cardinality-based ranking.

Collective Identification Procedures (CIPs) model admission rules regulating membership in associations, communities and clubs: the Libertarian identification rule Fl is the CIP which essentially relies on self-certification. This paper studies Fl in an arbitrary finite atomistic lattice,...

It is shown that a social choice rule f : X^N ? X as defined on a bounded distributive lattice (X, ) is strategy-proof on the set of all profiles of unimodal total preorders on X if and only if it can be represented as an iterated median of projections and constants. The equivalence of individual...

It is shown that the median voter theorem for committee-decisions holds over a full unimodal preference domain whenever (i) the underlying median interval space satisfi?es interval antiexchange and (ii) unimodality is defi?ned with respect to the incidence-geometry of the relevant outcome space...

A choice function is (weakly) width-maximizing if there exists a dissimilarity- i.e. an irreflexive symmetric binary relation- on the underlying object set such that the choice sets are (include, respectively) dissimilarity chains of locally maximum size. Width-maximizing and weakly...

We consider an extension of the class of multi-utility hyper-relations, the class of semidecent hyper-relations. A semi-decent hyper-relation satisfies monotonicity, stability with respect to contraction, and the union property. We analyze the class of semi-decent hyper-relations both...

It is shown that simple and coalitional strategy-proofness of a voting rule as defi?ned on the full unimodal domain of a convex idempotent interval space (X; I) are equivalent properties if (X; I) satis?es interval anti-exchange, a basic property also shared by a large class of convex geometries...

It is shown that a two-valued and nonsovereign voting rule is strategy-proof on any preference domain that includes all pro?les of total preorders with a unique maximum if and only if votes for noneligible feasible alternatives are only available to dummy voters. It follows that dummy-free...

The concept lattice of a coalitional game form is introduced and advocated as a structural classificatory tool. The basic properties of such lattices are studied. Sufficient concept-latticial properties for convexity of the underlying coalitional game form are identified. Spectral issues...

It is shown that concept lattices can be attached in a natural way to any voting protocol. The concept lattices of some voting protocols that are solvable with respect to some prominnent solution concepts and outcome-efficient are studied: it is proved that they typically amount to chains