The art gallery problem is∃ ℝ-complete

M Abrahamsen, A Adamaszek, T Miltzow - ACM Journal of the ACM …, 2021 - dl.acm.org
Given a simple polygon P, we say that two points p, q∈ P see each other if the line segment
pq is contained in P. A set of points G⊆ P is said to guard the polygon P if every point p∈ P …

Training neural networks is ER-complete

M Abrahamsen, L Kleist… - Advances in Neural …, 2021 - proceedings.neurips.cc
Given a neural network, training data, and a threshold, finding weights for the neural network
such that the total error is below the threshold is known to be NP-hard. We determine the …

Smoothing the gap between NP and ER

J Erickson, I Van Der Hoog, T Miltzow - SIAM Journal on Computing, 2022 - SIAM
We study algorithmic problems that belong to the complexity class of the existential theory of
the reals (∃R). A problem is\ensuremath ∃\mathbbR-complete if it is as hard as the …

Covering polygons is even harder

M Abrahamsen - 2021 IEEE 62nd Annual Symposium on …, 2022 - ieeexplore.ieee.org
In the Minimum Convex Cover (MCC) problem, we are given a simple polygon P and an
integer k, and the question is if there exist k convex polygons whose union is P. It is known …

The complexity of the Hausdorff distance

P Jungeblut, L Kleist, T Miltzow - Discrete & Computational Geometry, 2024 - Springer
We investigate the computational complexity of computing the Hausdorff distance.
Specifically, we show that the decision problem of whether the Hausdorff distance of two …

Framework for -Completeness of Two-Dimensional Packing Problems

M Abrahamsen, T Miltzow, N Seiferth - TheoretiCS, 2024 - theoretics.episciences.org
The aim in packing problems is to decide if a given set of pieces can be placed inside a
given container. A packing problem is defined by the types of pieces and containers to be …

On classifying continuous constraint satisfaction problems

T Miltzow, RF Schmiermann - TheoretiCS, 2024 - theoretics.episciences.org
A continuous constraint satisfaction problem (CCSP) is a constraint satisfaction problem
(CSP) with the real numbers as domain. We engage in a systematic study to classify CCSPs …

The existential theory of the reals as a complexity class: A compendium

M Schaefer, J Cardinal, T Miltzow - arXiv preprint arXiv:2407.18006, 2024 - arxiv.org
We survey the complexity class $\exists\mathbb {R} $, which captures the complexity of
deciding the existential theory of the reals. The class $\exists\mathbb {R} $ has roots in two …

Geometric Embeddability of Complexes is∃ ℝ-complete

M Abrahamsen, L Kleist, T Miltzow - Journal of the ACM, 2023 - dl.acm.org
We show that the decision problem of determining whether a given (abstract simplicial)-
complex has a geometric embedding in is complete for the Existential Theory of the Reals …

Computing exact solutions of consensus halving and the Borsuk-Ulam theorem

A Deligkas, J Fearnley, T Melissourgos… - Journal of Computer and …, 2021 - Elsevier
We study the problem of finding an exact solution to the Consensus Halving problem. While
recent work has shown that the approximate version of this problem is PPA-complete …