Fair in the Eyes of Others

Envy-freeness is a widely studied notion in resource allocation, capturing some aspects of fairness. The envy being inherently subjective though, it might be the case that an agent envies another agent, but from other agents' point view, she has no reason to do so. difficulty here define objectivity, since ground-truth can properly serve as basis this definition. A natural approach consider judgement agents proxy for objectivity. Building on previous work by Parijs (who introduced "unanimous envy") we propose approval envy: ai experiences towards aj if envious aj, and sufficiently many agree should case, their own perspectives. Another thoroughly allocation proportionality. same variant studied, opening questions regarding links between these two notions. We exhibit several properties Computing minimal threshold guaranteeing non-proportionality clearly inherits well-known intractable results envy-freeness proportionality, (i) identify tractable cases such house allocation; (ii) provide general method based mixed integer programming encoding problem, which proves efficient practice. This allows us particular show experimentally existence allocations, with rather small threshold, very often observed.