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Christian Sohler

7 accepted papers

2026

Learning to Approximate Uniform Facility Location via Graph Neural Networks

ICML 2026poster

There has been a growing interest in using neural networks, especially message-passing neural networks (MPNNs), to solve hard combinatorial optimization problems heuristically. However, existing learning-based approaches for hard combinatorial optimization tasks often rely on supervised training dat…

Cited by 0SourceScholar
2025

A Subquadratic Time Approximation Algorithm for Individually Fair k-Center

AISTATS 2025poster

We study the $k$-center problem in the context of individual fairness. Let $P$ be a set of $n$ points in a metric space and $r_x$ be the distance between $x \in P$ and its $\lceil n/k \rceil$-th nearest neighbor. The problem asks to optimize the $k$-center objective under the constraint that, for e…

Cited by 0SourceScholar
2021

Parallel and Efficient Hierarchical k-Median Clustering

NeurIPS 2021poster

As a fundamental unsupervised learning task, hierarchical clustering has been extensively studied in the past decade. In particular, standard metric formulations as hierarchical $k$-center, $k$-means, and $k$-median received a lot of attention and the problems have been studied extensively in diffe…

Cited by 8SourcePDFScholar
2020

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

NeurIPS 2020poster

$k$-means++ \cite{arthur2007k} is a widely used clustering algorithm that is easy to implement, has nice theoretical guarantees and strong empirical performance. Despite its wide adoption, $k$-means++ sometimes suffers from being slow on large data-sets so a natural question has been to obtain more…

Cited by 27SourcePDFScholar
2018

On Coresets for Logistic Regression

NeurIPS 2018spotlight

Coresets are one of the central methods to facilitate the analysis of large data. We continue a recent line of research applying the theory of coresets to logistic regression. First, we show the negative result that no strongly sublinear sized coresets exist for logistic regression. To deal with int…

Cited by 126SourcePDFScholar
2017

Clustering High Dimensional Dynamic Data Streams

ICML 2017poster

We present data streaming algorithms for the $k$-median problem in high-dimensional dynamic geometric data streams, i.e. streams allowing both insertions and deletions of points from a discrete Euclidean space $\{1, 2, \ldots \Delta\}^d$. Our algorithms use $k \epsilon^{-2} \mathrm{poly}(d \log \Del…

Cited by 64SourcePDFScholar