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| author | Stratis Ioannidis <stratis@stratis-Latitude-E6320.(none)> | 2013-07-07 21:21:23 -0700 |
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| committer | Stratis Ioannidis <stratis@stratis-Latitude-E6320.(none)> | 2013-07-07 21:21:23 -0700 |
| commit | 8562564268f83ca4ea0a4d6cd316a61f8b66f6b2 (patch) | |
| tree | c49c9499bc314ccb386c2380b5514cc66f50e583 /problem.tex | |
| parent | 56ef116dcbe0d4b81f7b5bc2d38d9d51add2c62a (diff) | |
| download | recommendation-8562564268f83ca4ea0a4d6cd316a61f8b66f6b2.tar.gz | |
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| -rw-r--r-- | problem.tex | 12 |
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diff --git a/problem.tex b/problem.tex index 1001d7b..8d5b262 100644 --- a/problem.tex +++ b/problem.tex @@ -84,13 +84,9 @@ covariance matrices $R$ can be found in Appendix~\ref{sec:ext}. \subsection{Budget-Feasible Experimental Design: Full Information Case}\label{sec:fullinfo} -Beyond the cardinality constraint in classical experimental design discussed above, a - budgeted version can also be considered. -%depart from the above classic experimental design setting by assuming that -Each experiment is associated with a cost $c_i\in\reals_+$. Moreover, the experimenter $\E$ is limited by a budget $B\in \reals_+$. -The cost $c_i$ can capture, \emph{e.g.}, the amount the subject $i$ deems sufficient to -incentivize her participation in the experiment. -In the full-information case, the experiment costs are common knowledge; as such, the optimization problem that the experimenter wishes to solve is: +Instead of the cardinality constraint in classical experimental design discussed above, we consider a budget-constrained version. +Each experiment is associated with a cost $c_i\in\reals_+$. +The cost $c_i$ can capture, \emph{e.g.}, the amount the subject $i$ deems sufficient to incentivize her participation in the experiment. The experimenter $\E$ is limited by a budget $B\in \reals_+$. In the full-information case, experiment costs are common knowledge; as such, the experimenter wishes to solve: \medskip\\\hspace*{\stretch{1}}\textsc{ExperimentalDesignProblem} (\EDP)\hspace*{\stretch{1}} \begin{subequations} \begin{align} @@ -149,7 +145,7 @@ We seek mechanisms that are \emph{normalized} (unallocated experiments receive z We relax the notion of truthfulness to \emph{$\delta$-truthfulness}, requiring that reporting one's true cost is an \emph{almost-dominant} strategy: no subject increases their utility by reporting a cost that differs more than $\delta>0$ from their true cost. Under this definition, a mechanism is truthful if $\delta=0$. In addition, we would like the allocation $S(c)$ to be of maximal value; however, $\delta$-truthfulness, as well as the hardness of \EDP{}, preclude achieving this goal. Hence, we seek mechanisms with that yield a \emph{constant approximation ratio}, \emph{i.e.}, there exists $\alpha\geq 1$ s.t.~$OPT \leq \alpha V(S(c))$, and are \emph{computationally efficient}, in that $S$ and $p$ can be computed in polynomial time. -We note that the $\max$ operator in the greedy algorithm \eqref{eq:max-algorithm} breaks +We note that the greedy algorithm \eqref{eq:max-algorithm} breaks truthfulness. Though this is not true for all submodular functions (see, \emph{e.g.}, \cite{singer-mechanisms}), it is true for the objective of \EDP{}: we show this in Appendix~\ref{sec:non-monotonicity}. This motivates our study of more complex mechanisms. \begin{comment} |
