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Are all subcorrespondences of the weak Pareto correspondence monotonic at the unrestricted domain of linear orders?

I have a doubt regarding the well-known concepts of weak Pareto optimality and monotonicity.

Let $N$ be a finite set of players, let $A$ be a finite set of alternatives, let $\mathcal{P}$ be the set of all linear order profiles on $A$, and let $F:\mathcal{P}\to 2^A\backslash\{\emptyset\}$ be a social choice correspondence.

Let $F^*:\mathcal{P}\to 2^A\backslash\{\emptyset\}$ be the weak Pareto correspondence: namely, for all linear order profiles $P\in\mathcal{P}$, \begin{gather} F^*(P)=\{x\in A\mid(\nexists y\in A)[(\forall i\in N)(yP_ix)]\} \end{gather}

Given any player $i\in N$, any alternative $x\in A$ and any linear order profile $P\in\mathcal{P}$, let $L_i(x,P)=\{y\in A\mid xP_iy\}$ be player $i$'s lower contour set at $x$.

A social choice rule $F:\mathcal{P}^N\to 2^A\backslash\{\emptyset\}$ is monotonic if and only if for all alternatives $x\in A$ and all linear order profiles $P,P'\in\mathcal{P}$, the following is true: if $x\in F(P)$ and $L_i(x,P)\subseteq L_i(x,P')$ for all $i\in N$, then $x\in F(P')$.

We know by Maskin & Sjöström (Footnote 15, p. 248, 2002) that the weak Pareto correspondence is monotonic at the unrestricted domain of linear orders.

What I am wondering is whether all subcorrespondences of the weak Pareto correspondence is also monotonic at the unrestricted domain of linear orders.

Answer

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  • $\begingroup$ Thank you very much for your answer. I have edited the body of the question to ensure it matches the question in the title. $\endgroup$
    – EoDmnFOr3q
    Commented Jul 7 at 7:55

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