Search Results for author: Ola Svensson

Found 10 papers, 2 papers with code

An Analysis of $D^α$ seeding for $k$-means

no code implementations20 Oct 2023 Etienne Bamas, Sai Ganesh Nagarajan, Ola Svensson

For any $\alpha>2$, we show that $D^\alpha$ seeding guarantees in expectation an approximation factor of $$ O_\alpha \left((g_\alpha)^{2/\alpha}\cdot \left(\frac{\sigma_{\mathrm{max}}}{\sigma_{\mathrm{min}}}\right)^{2-4/\alpha}\cdot (\min\{\ell,\log k\})^{2/\alpha}\right)$$ with respect to the standard $k$-means cost of any underlying clustering; where $g_\alpha$ is a parameter capturing the concentration of the points in each cluster, $\sigma_{\mathrm{max}}$ and $\sigma_{\mathrm{min}}$ are the maximum and minimum standard deviation of the clusters around their means, and $\ell$ is the number of distinct mixing weights in the underlying clustering (after rounding them to the nearest power of $2$).

Clustering

Parallel and Efficient Hierarchical k-Median Clustering

no code implementations NeurIPS 2021 Vincent Cohen-Addad, Silvio Lattanzi, Ashkan Norouzi-Fard, Christian Sohler, Ola Svensson

In this paper we introduce a new parallel algorithm for the Euclidean hierarchical $k$-median problem that, when using machines with memory $s$ (for $s\in \Omega(\log^2 (n+\Delta+d))$), outputs a hierarchical clustering such that for every fixed value of $k$ the cost of the solution is at most an $O(\min\{d, \log n\} \log \Delta)$ factor larger in expectation than that of an optimal solution.

Clustering

Nearly-Tight and Oblivious Algorithms for Explainable Clustering

no code implementations NeurIPS 2021 Buddhima Gamlath, Xinrui Jia, Adam Polak, Ola Svensson

We give an algorithm that outputs an explainable clustering that loses at most a factor of $O(\log^2 k)$ compared to an optimal (not necessarily explainable) clustering for the $k$-medians objective, and a factor of $O(k \log^2 k)$ for the $k$-means objective.

Clustering

Semi-Streaming Algorithms for Submodular Matroid Intersection

no code implementations8 Feb 2021 Paritosh Garg, Linus Jordan, Ola Svensson

Their approach is based on the versatile local ratio technique and also applies to generalizations such as weighted hypergraph matchings.

Data Structures and Algorithms

Fast and Accurate $k$-means++ via Rejection Sampling

no code implementations NeurIPS 2020 Vincent Cohen-Addad, Silvio Lattanzi, Ashkan Norouzi-Fard, Christian Sohler, Ola Svensson

$k$-means++ \cite{arthur2007k} is a widely used clustering algorithm that is easy to implement, has nice theoretical guarantees and strong empirical performance.

Clustering

The Primal-Dual method for Learning Augmented Algorithms

1 code implementation NeurIPS 2020 Étienne Bamas, Andreas Maggiori, Ola Svensson

The extension of classical online algorithms when provided with predictions is a new and active research area.

Learning Augmented Energy Minimization via Speed Scaling

1 code implementation NeurIPS 2020 Étienne Bamas, Andreas Maggiori, Lars Rohwedder, Ola Svensson

As power management has become a primary concern in modern data centers, computing resources are being scaled dynamically to minimize energy consumption.

BIG-bench Machine Learning Management

Beyond $1/2$-Approximation for Submodular Maximization on Massive Data Streams

no code implementations6 Aug 2018 Ashkan Norouzi-Fard, Jakub Tarnawski, Slobodan Mitrović, Amir Zandieh, Aida Mousavifar, Ola Svensson

It is the first low-memory, single-pass algorithm that improves the factor $0. 5$, under the natural assumption that elements arrive in a random order.

Clustering Recommendation Systems

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