• The computational complexity of understanding binary classifier decisions 

      Wäldchen, Stephan; Macdonald, Jan; Hauch, Sascha; Kutyniok, Gitta Astrid Hildegard (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-21)
      For a d-ary Boolean function Φ: {0, 1}<sup>d</sup> → {0, 1} and an assignment to its variables x = (x<sub>1</sub>, x<sub>2</sub>, . . . , x<sub>d</sub>) we consider the problem of finding those subsets of the variables that are sufficient to determine the function value with a given probability δ. This is motivated by the task of interpreting predictions of binary classifiers described as Boolean ...
    • Deep microlocal reconstruction for limited-angle tomography 

      Andrade-Loarca, Héctor; Kutyniok, Gitta Astrid Hildegard; Öktem, Ozan; Petersen, Philipp (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-04)
      We present a deep-learning-based algorithm to jointly solve a reconstruction problem and a wavefront set extraction problem in tomographic imaging. The algorithm is based on a recently developed digital wavefront set extractor as well as the well-known microlocal canonical relation for the Radon transform. We use the wavefront set information about x-ray data to improve the reconstruction ...
    • Numerical Solution of the Parametric Diffusion Equation by Deep Neural Networks 

      Geist, Moritz; Petersen, Philipp; Raslan, Mones; Schneider, Reinhold; Kutyniok, Gitta Astrid Hildegard (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-05)
      We perform a comprehensive numerical study of the effect of approximation-theoretical results for neural networks on practical learning problems in the context of numerical analysis. As the underlying model, we study the machine-learning-based solution of parametric partial differential equations. Here, approximation theory for fully-connected neural networks predicts that the performance of the ...
    • Quasi Monte Carlo time-frequency analysis 

      Levie, Ron; Avron, Haim; Kutyniok, Gitta Astrid Hildegard (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-30)
      We study signal processing tasks in which the signal is mapped via some generalized time-frequency transform to a higher dimensional time-frequency space, processed there, and synthesized to an output signal. We show how to approximate such methods using a quasi-Monte Carlo (QMC) approach. We consider cases where the time-frequency representation is redundant, having feature axes in addition to the ...
    • Real-Time Outdoor Localization Using Radio Maps: A Deep Learning Approach 

      Yapar, Cagkan; Levie, Ron; Kutyniok, Gitta Astrid Hildegard; Caire, Giuseppe (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-10)
      Global Navigation Satellite Systems typically perform poorly in urban environments, where the likelihood of line-of-sight conditions between devices and satellites is low. Therefore, alternative location methods are required to achieve good accuracy. We present LocUNet: A convolutional, end-to-end trained neural network (NN) for the localization task, which is able to estimate the position of a user ...
    • Shearlets as feature extractor for semantic edge detection: The model-based and data-driven realm: Shearlets for Semantic Edge Detection 

      Andrade-Loarca, Héctor; Kutyniok, Gitta Astrid Hildegard; Öktem, Ozan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-25)
      Semantic edge detection has recently gained a lot of attention as an image-processing task, mainly because of its wide range of real-world applications. This is based on the fact that edges in images contain most of the semantic information. Semantic edge detection involves two tasks, namely pure edge detection and edge classification. Those are in fact fundamentally distinct in terms of the level ...
    • A Theoretical Analysis of Deep Neural Networks and Parametric PDEs 

      Kutyniok, Gitta Astrid Hildegard; Petersen, Philipp; Raslan, Mones; Schneider, Reinhold (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-02)
      We derive upper bounds on the complexity of ReLU neural networks approximating the solution maps of parametric partial differential equations. In particular, without any knowledge of its concrete shape, we use the inherent low dimensionality of the solution manifold to obtain approximation rates which are significantly superior to those provided by classical neural network approximation results. ...
    • Transferability of graph neural networks: An extended graphon approach 

      Maskey, Sohir; Levie, Ron; Kutyniok, Gitta Astrid Hildegard (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-28)
      We study spectral graph convolutional neural networks (GCNNs), where filters are defined as continuous functions of the graph shift operator (GSO) through functional calculus. A spectral GCNN is not tailored to one specific graph and can be transferred between different graphs. It is hence important to study the GCNN transferability: the capacity of the network to have approximately the same ...
    • Unification of sparse Bayesian learning algorithms for electromagnetic brain imaging with the majorization minimization framework 

      Hashemi, Ali; Cai, Chang; Kutyniok, Gitta Astrid Hildegard; Müller, Klaus R.; Nagarajan, Srikantan S.; Haufe, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-01)
      Methods for electro- or magnetoencephalography (EEG/MEG) based brain source imaging (BSI) using sparse Bayesian learning (SBL) have been demonstrated to achieve excellent performance in situations with low numbers of distinct active sources, such as event-related designs. This paper extends the theory and practice of SBL in three important ways. First, we reformulate three existing SBL algorithms ...