summaryrefslogtreecommitdiffstats
path: root/main.tex
diff options
context:
space:
mode:
authorThibaut Horel <thibaut.horel@gmail.com>2013-02-10 16:52:24 -0800
committerThibaut Horel <thibaut.horel@gmail.com>2013-02-10 16:52:24 -0800
commitdf1a97cb16319a2e4eb151574d3a2f9038682e8e (patch)
tree626cc757716dc0e5c7e242448ef6970cf41c8562 /main.tex
parent2435d66feaaccea1b1cdf289b9e8305692d14dd0 (diff)
downloadrecommendation-df1a97cb16319a2e4eb151574d3a2f9038682e8e.tar.gz
Small fixes in main section up to the subsection 4.2
Diffstat (limited to 'main.tex')
-rw-r--r--main.tex22
1 files changed, 11 insertions, 11 deletions
diff --git a/main.tex b/main.tex
index 8c57916..64d4604 100644
--- a/main.tex
+++ b/main.tex
@@ -138,10 +138,10 @@ set can be found in~\cite{singer-mechanisms}.
\begin{algorithmic}[1]
\State $\mathcal{N} \gets \mathcal{N}\setminus\{i\in\mathcal{N} : c_i > B\}$
\State $i^* \gets \argmax_{j\in\mathcal{N}}V(j)$
- \State $\xi \gets \argmax_{\lambda\in[0,1]^{n}} \{L(\lambda)
+ \State $L^* \gets \argmax_{\lambda\in[0,1]^{n}} \{L(\lambda)
\mid \lambda_{i^*}=0,\sum_{i \in \mathcal{N}\setminus\{i^*\}}c_i\lambda_i\leq B\}$
\Statex
- \If{$L(\xi) < C \cdot V(i^*)$} \label{c}
+ \If{$L^* < C \cdot V(i^*)$} \label{c}
\State \textbf{return} $\{i^*\}$
\Else
\State $i \gets \argmax_{1\leq j\leq n}\frac{V(j)}{c_j}$
@@ -227,18 +227,18 @@ in the above formula:
\lambda_i x_i\T{x_i}\right)
\end{align}
\end{comment}
+
\subsection{Proof of Theorem~\ref{thm:main}}\label{sec:proofofmainthm}
%\stratis{individual rationality???}
%The proof of the properties of the mechanism is broken down into lemmas.
We now present the proof of Theorem~\ref{thm:main}. Truthfulness and individual
rationality follows from monotonicity and threshold payments. Monotonicity and
-budget feasibility follow the same steps as the analysis of Chen \emph{et al.} \cite{chen};
+budget feasibility follow the same steps as the analysis of \citeN{chen};
for the sake of completeness, we restate their proof in the Appendix.
- Our proof of the approximation ratio uses a bound on our concave relaxation
-$L$ (Lemma~\ref{lemma:relaxation}). This is our main technical
-contribution; the proof of this lemma can be found in Section~\ref{sec:relaxation}.
-\begin{lemma}\label{lemma:complexity}
+
+The complexity of the mechanism is given by the following lemma.
+\begin{lemma}[Complexity]\label{lemma:complexity}
For any $\varepsilon > 0$, the complexity of the mechanism is
$O(\text{poly}(n, d, \log\log \varepsilon^{-1}))$.
\end{lemma}
@@ -264,7 +264,7 @@ contribution; the proof of this lemma can be found in Section~\ref{sec:relaxatio
Finally, we prove the approximation ratio of the mechanism. We use the
following lemma which establishes that $OPT'$, the optimal value \eqref{relax} of the fractional relaxation $L$ under the budget constraints
is not too far from $OPT$.
-\begin{lemma}\label{lemma:relaxation}
+\begin{lemma}[Approximation]\label{lemma:relaxation}
%\begin{displaymath}
$ OPT' \leq 2 OPT
+ 2\max_{i\in\mathcal{N}}V(i)$
@@ -317,11 +317,11 @@ Using Lemma~\ref{lemma:relaxation} we can complete the proof of Theorem~\ref{thm
+ \frac{(e-1)\varepsilon}{C(e-1)- 6e + 2}
\end{align*}
Finally, using again Lemma~\ref{lemma:greedy-bound}, we get:
- \begin{multline}\label{eq:bound2}
+ \begin{equation}\label{eq:bound2}
OPT(V, \mathcal{N}, B) \leq \frac{3e}{e-1}\left( 1 + \frac{4e}{C
- (e-1) -6e +2}\right) V(S_G)\\
+ (e-1) -6e +2}\right) V(S_G)
+\frac{2e\varepsilon}{C(e-1)- 6e + 2}
- \end{multline}
+ \end{equation}
To minimize the coefficients of $V_{i^*}$ and $V(S_G)$ in \eqref{eq:bound1} and \eqref{eq:bound2} respectively,
we wish to chose for $C=C^*$ such that:
\begin{displaymath}