Fair and efficient allocations when preferences are single-dipped

One unit of an infinitely divisible and non-disposable commodity has to be allocated among a group of agents with single-dipped preferences. We combine Pareto optimality with equal treatment of equals, the equal division lower bound, the equal division core, envy-freeness, and group envy-freeness. For each of these fairness requirements, we provide a necessary and sufficient condition for compatibility with Pareto optimality and we characterize all corresponding allocations for each preference profile.