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authorThibaut Horel <thibaut.horel@gmail.com>2013-06-10 19:09:15 +0200
committerThibaut Horel <thibaut.horel@gmail.com>2013-06-10 19:09:15 +0200
commit7ff4a4d46dbd64cd8bc7c07d0c7f11f13779443c (patch)
tree185567c1d8dbbe22ca7c7696887a4931c46e7818 /appendix.tex
parent6a7822112496198f118bdcedc2600f6b6770dd39 (diff)
downloadrecommendation-7ff4a4d46dbd64cd8bc7c07d0c7f11f13779443c.tar.gz
Moving our two main results to a section preceding the introduction of our mechanism
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@@ -22,7 +22,8 @@ Our mechanism for \EDP{} is monotone and budget feasible.
\frac{B}{2}\frac{V(S_i\cup\{i\})-V(S_i)}{V(S_i\cup\{i\})}
\leq \frac{B}{2}\frac{V(S_i'\cup\{i\})-V(S_i')}{V(S_i'\cup\{i\})}
\end{align*}
- by the monotonicity and submodularity of $V$. Hence $i\in S_G'$. As $OPT'_{-i^*}$, is the optimal value of \eqref{relax} under relaxation $L$ when $i^*$ is excluded from $\mathcal{N}$, reducing the costs can only increase this value, so under $c'_i\leq c_i$ the greedy set is still allocated and $s_i(c_i',c_{-i}) =1$.
+ by the monotonicity and submodularity of $V$. Hence $i\in S_G'$. As
+ $OPT'_{-i^*}$, is the optimal value of \eqref{eq:primal} under relaxation $L$ when $i^*$ is excluded from $\mathcal{N}$, reducing the costs can only increase this value, so under $c'_i\leq c_i$ the greedy set is still allocated and $s_i(c_i',c_{-i}) =1$.
Suppose now that when $i$ reports $c_i$, $OPT'_{-i^*} < C V(i^*)$. Then $s_i(c_i,c_{-i})=1$ iff $i = i^*$.
Reporting $c_{i^*}'\leq c_{i^*}$ does not change $V(i^*)$ nor
$OPT'_{-i^*} \leq C V(i^*)$; thus $s_{i^*}(c_{i^*}',c_{-i^*})=1$, so the mechanism is monotone.