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We introduce a graph partitioning problem motivated by computational topology and propose two algorithms that produce approximate solutions. Specifically, given a weighted, undirected graph $G$ and a positive integer $k$, we desire to find…

Combinatorics · Mathematics 2019-07-04 Abdel-Rahman Madkour , Phillip Nadolny , Matthew Wright

We prove that there is a randomized polynomial-time algorithm that given an edge-weighted graph $G$ excluding a fixed-minor $Q$ on $n$ vertices and an accuracy parameter $\varepsilon>0$, constructs an edge-weighted graph~$H$ and an…

Data Structures and Algorithms · Computer Science 2023-04-17 Vincent Cohen-Addad , Hung Le , Marcin Pilipczuk , Michał Pilipczuk

We study the private $k$-median and $k$-means clustering problem in $d$ dimensional Euclidean space. By leveraging tree embeddings, we give an efficient and easy to implement algorithm, that is empirically competitive with state of the art…

An L-shaped embedding of a tree in a point set is a planar drawing of the tree where the vertices are mapped to distinct points and every edge is drawn as a sequence of two axis-aligned line segments. There has been considerable work on…

Computational Geometry · Computer Science 2020-05-01 Torsten Mütze , Manfred Scheucher

Outlier detection algorithms typically assign an outlier score to each observation in a dataset, indicating the degree to which an observation is an outlier. However, these scores are often not comparable across algorithms and can be…

Machine Learning · Computer Science 2024-10-31 Philipp Röchner , Henrique O. Marques , Ricardo J. G. B. Campello , Arthur Zimek , Franz Rothlauf

The Whitney embedding theorem gives an upper bound on the smallest embedding dimension of a manifold. If a data set lies on a manifold, a random projection into this reduced dimension will retain the manifold structure. Here we present an…

Machine Learning · Statistics 2017-11-06 David W. Dreisigmeyer

In this work we perform outlier detection using ensembles of neural networks obtained by variational approximation of the posterior in a Bayesian neural network setting. The variational parameters are obtained by sampling from the true…

Machine Learning · Statistics 2017-04-25 Nick Pawlowski , Miguel Jaques , Ben Glocker

Low-dimensional embedding, manifold learning, clustering, classification, and anomaly detection are among the most important problems in machine learning. The existing methods usually consider the case when each instance has a fixed,…

Machine Learning · Computer Science 2012-02-20 Barnabas Poczos , Liang Xiong , Jeff Schneider

We initiate a comprehensive experimental study of objective-based hierarchical clustering methods on massive datasets consisting of deep embedding vectors from computer vision and NLP applications. This includes a large variety of image…

Machine Learning · Computer Science 2022-06-10 Stanislav Naumov , Grigory Yaroslavtsev , Dmitrii Avdiukhin

Constrained clustering problems generalize classical clustering formulations, e.g., $k$-median, $k$-means, by imposing additional constraints on the feasibility of clustering. There has been significant recent progress in obtaining…

Data Structures and Algorithms · Computer Science 2025-04-22 Ragesh Jaiswal , Amit Kumar

Under which conditions and with which distortions can we preserve the pairwise-distances of low-complexity vectors, e.g., for structured sets such as the set of sparse vectors or the one of low-rank matrices, when these are mapped in a…

Information Theory · Computer Science 2016-11-15 Laurent Jacques

We prove that given a discrete space with $n$ points which is either embedded in a system of $k$ trees, or the Cartesian product of $k$ trees, we can compute all eccentricities in ${\cal O}(2^{{\cal O}(k\log{k})}(N+n)^{1+o(1)})$ time, where…

Data Structures and Algorithms · Computer Science 2020-10-30 Guillaume Ducoffe

Clustering and outlier detection are two important tasks in data mining. Outliers frequently interfere with clustering algorithms to determine the similarity between objects, resulting in unreliable clustering results. Currently, only a few…

Machine Learning · Computer Science 2024-12-10 Qi Li , Shuliang Wang

We study the inference of network archaeology in growing random geometric graphs. We consider the root finding problem for a random nearest neighbor tree in dimension $d \in \mathbb{N}$, generated by sequentially embedding vertices…

Probability · Mathematics 2024-11-22 Anna Brandenberger , Cassandra Marcussen , Elchanan Mossel , Madhu Sudan

The $k$-center problem for a point set~$P$ asks for a collection of $k$ congruent balls (that is, balls of equal radius) that together cover all the points in $P$ and whose radius is minimized. The $k$-center problem with outliers is…

Computational Geometry · Computer Science 2021-09-27 Mark de Berg , Morteza Monemizadeh , Yu Zhong

We consider a fundamental problem in unsupervised learning called \emph{subspace recovery}: given a collection of $m$ points in $\mathbb{R}^n$, if many but not necessarily all of these points are contained in a $d$-dimensional subspace $T$…

Computational Complexity · Computer Science 2013-12-05 Moritz Hardt , Ankur Moitra

Outlier detection has gained increasing interest in recent years, due to newly emerging technologies and the huge amount of high-dimensional data that are now available. Outlier detection can help practitioners to identify unwanted noise…

Statistics Theory · Mathematics 2021-05-20 Mads Lindskou , Torben Tvedebrink , Poul Svante Eriksen , Niels Morling

Out-of-distribution (OOD) detection is an important task in machine learning systems for ensuring their reliability and safety. Deep probabilistic generative models facilitate OOD detection by estimating the likelihood of a data sample.…

Machine Learning · Computer Science 2021-06-16 Jaemoo Choi , Changyeon Yoon , Jeongwoo Bae , Myungjoo Kang

Outlier detection in a large-scale database is a significant and complex issue in knowledge discovering field. As the data distributions are obscure and uncertain in high dimensional space, most existing solutions try to solve the issue…

Artificial Intelligence · Computer Science 2014-05-06 Zhana Bao

The tree inclusion problem is, given two node-labeled trees $P$ and $T$ (the ``pattern tree'' and the ``target tree''), to locate every minimal subtree in $T$ (if any) that can be obtained by applying a sequence of node insertion operations…

Data Structures and Algorithms · Computer Science 2021-06-16 Tatsuya Akutsu , Jesper Jansson , Ruiming Li , Atsuhiro Takasu , Takeyuki Tamura