diff --git a/paper/references.bib b/paper/references.bib index cb1f982..df4a9e0 100644 --- a/paper/references.bib +++ b/paper/references.bib @@ -144,6 +144,19 @@ number = {2} } +@article{khullerBudgetedMaximumCoverage1999, + title = {The Budgeted Maximum Coverage Problem}, + author = {Khuller, Samir and Moss, Anna and Naor, Joseph}, + year = {1999}, + month = apr, + volume = {70}, + pages = {39--45}, + doi = {10.1016/S0020-0190(99)00031-9}, + abstract = {The budgeted maximum coverage problem is: given a collection S of sets with associated costs defined over a domain of weighted elements, and a budget L, find a subset of S{${'}\subseteqq$}S such that the total cost of sets in S{${'}$} does not exceed L, and the total weight of elements covered by S{${'}$} is maximized. This problem is NP-hard. For the special case of this problem, where each set has unit cost, a (1-1/e)-approximation is known. Yet, prior to this work, no approximation results were known for the general cost version. The contribution of this paper is a (1-1/e)-approximation algorithm for the budgeted maximum coverage problem. We also argue that this approximation factor is the best possible, unless NP{$\subseteqq$}DTIME(nO(loglogn)).}, + journal = {Information Processing Letters}, + number = {1} +} + @inproceedings{langPortioningUsingOrdinal2019, title = {Portioning {{Using Ordinal Preferences}}: {{Fairness}} and {{Efficiency}}}, shorttitle = {Portioning {{Using Ordinal Preferences}}}, diff --git a/paper/termpaper.tex b/paper/termpaper.tex index 9debd7e..8420f34 100644 --- a/paper/termpaper.tex +++ b/paper/termpaper.tex @@ -333,6 +333,28 @@ constant time. however, gives $\{ p_2,p_3,p_4 \}$. \end{example} +A benefit of the three discussed satisfaction functions is that they can be +viewed as constraint satisfaction problems (CSPs) and can thus be formulated +using integer linear programming (ILP). Although integer programming is +\textsf{NP}-complete, efficient solvers are readily available for these types of +problems. \textcite{talmonFrameworkApprovalBasedBudgeting2019} show that the +rule $\mathcal{R}_{sat_{0/1}}^m$ is similar to the max cover problem which can +be approximated with a $(1-\frac{1}{e})$-approximation algorithm. In fact, +\textcite{khullerBudgetedMaximumCoverage1999} show that an approximation +algorithm with the same ratio exists not only for the case where the projects +have unit cost but also for the general cost version. + +Instead of sacrificing exactness to get a better running time, +\textcite{talmonFrameworkApprovalBasedBudgeting2019} show that the +$\mathcal{R}_{sat_{0/1}}^m$ rule is fixed parameter tractable for the number of +voters $|V|$. A problem is fixed parameter tractable if there exists an +algorithm that decides each instance of the problem in $O(f(k)\cdot p(n))$ where +$p(n)$ is a polynomial function and $f(k)$ an arbitrary function in $k$. It is +crucial to note that $f(k)$ does not admit functions of the form $n^k$. The +algorithm for the maximum rule tries to guess the number of voters that are +represented by the same project. The estimation is then used to pick a project +which has the lowest cost and satisfies exactly the estimated amount of voters. + \printbibliography \end{document}