Justified representation: Difference between revisions
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==Implications== |
==Implications== |
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While [[approval voting]] is |
While [[approval voting]] is strategyproof for voters with dichotomous preferences,{{Cn}} every method passing justified representation is susceptible to strategic voting, even in this setting.<ref>{{cite arXiv | last=Peters | first=Dominik | title=Proportionality and Strategyproofness in Multiwinner Elections|eprint=2104.08594|class=cs.GT| date=2021-04-17}}</ref> |
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==Comparison== |
==Comparison== |
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Every winner set that provides [[Perfect representation]] also provides [[Justified representation | Proportional Justified Representation |
Every winner set that provides [[Perfect representation]] also provides [[Justified representation | Proportional Justified Representation]]<ref>{{cite web | last=Fernández | first=Sánchez | last2=García | first2=Fernández | last3=Fisteus | first3=Arias | last4=Val | first4=Basanta | title=Some notes on justified representation | website=e-Archivo Principal | date=2016-06-14 | url=https://e-archivo.uc3m.es/handle/10016/25680 | access-date=2022-04-30}}</ref>. In contrast, [[Justified representation | Extended Justified Representation ]] may rule out all winner sets that provide perfect representation. <ref>{{Cite arXiv|last=Aziz|first=Haris|last2=Brill|first2=Markus|last3=Conitzer|first3=Vincent|last4=Elkind|first4=Edith|last5=Freeman|first5=Rupert|last6=Walsh|first6=Toby|date=2016-09-11|title=Justified Representation in Approval-Based Committee Voting|eprint=1407.8269|class=cs.MA}}</ref> It is easily seen that PJR is a weaker requirement than EJR, and a stronger one than JR. A method satisfying EJR also satisfies PJR, and that a method satisfying PJR also satisfies JR. |
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Even though Justified representation may appear to be similar to [[Stable Winner Set | core stability]], it is, in fact, a strictly weaker condition. Indeed, the core stability condition appears to be too demanding, as no known voting system is guaranteed to produce a core stable outcome, even when the core is known to be non-empty. |
Even though Justified representation may appear to be similar to [[Stable Winner Set | core stability]], it is, in fact, a strictly weaker condition. Indeed, the core stability condition appears to be too demanding, as no known voting system is guaranteed to produce a core stable outcome, even when the core is known to be non-empty. |
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