Condorcet domains are sets of linear orders with the property that, whenever the preferences of all voters of a society belong to this set, their majority relation has no cycles. We observe that, without loss of generality, every such domain can be assumed to be closed in the sense that it...

In a conventional dial-a-ride-system passengers are moved with the same vehicle between their pickup and their drop-off location. In a dial-a-ride-system with transfer, it is possible (or even standard) that passengers change the vehicle once or several times. Transfer Scheduling Constraints...