Improved Bounds on Neural Complexity for Representing Piecewise Linear Functions
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Abstract (arXiv)
A deep neural network using rectified linear units represents a continuous piecewise linear (CPWL) function and vice versa. Recent results in the literature estimated that the number of neurons needed to exactly represent any CPWL function grows exponentially with the number of pieces or exponentially in terms of the factorial of the number of distinct linear components. Moreover, such growth is amplified linearly with the input dimension. These existing results seem to indicate that the cost of representing a CPWL function is expensive. In this paper, we propose much tighter bounds and establish a polynomial time algorithm to find a network satisfying these bounds for any given CPWL function. We prove that the number of hidden neurons required to exactly represent any CPWL function is at most a quadratic function of the number of pieces. In contrast to all previous results, this upper bound is invariant to the input dimension. Besides the number of pieces, we also study the number of distinct linear components in CPWL functions. When such a number is also given, we prove that the quadratic complexity turns into bilinear, which implies a lower neural complexity because the number of distinct linear components is always not greater than the minimum number of pieces in a CPWL function. When the number of pieces is unknown, we prove that, in terms of the number of distinct linear components, the neural complexities of any CPWL function are at most polynomial growth for low-dimensional inputs and factorial growth for the worst-case scenario, which are significantly better than existing results in the literature.
Key facts. Cited by 26 papers in the map (data through 7 Oct 2026). Builds on 22 of its 55 references that are in the map. First posted on arXiv 13 Oct 2022.
Builds on
22 of 55 references.
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- 2013Maxout Networkscited by 186
10 more
- 2015The Power of Depth for Feedforward Neural Networkscited by 181
- 2019Complexity of Linear Regions in Deep Networkscited by 166
- 2017Bounding and Counting Linear Regions of Deep Neural Networkscited by 161
- 2019Deep ReLU Networks Have Surprisingly Few Activation Patternscited by 160
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Citing papers per year: 2022: 1; 2023: 4; 2024: 6; 2025: 7; 2026: 8.
26 papers.
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- 2022Impossibility Theorems for Feature Attributioncited by 78
- 2023When Deep Learning Meets Polyhedral Theory: A Surveycited by 39
- 2023Deep Network Approximation: Beyond ReLU to Diverse Activation Functionscited by 33
- 2023Don't trust your eyes: on the (un)reliability of feature visualizationscited by 32
- 2024Model Reconstruction Using Counterfactual Explanations: A Perspective From Polytope Theorycited by 12
- 2024On Minimal Depth in Neural Networkscited by 11
- 2025Better Neural Network Expressivity: Subdividing the Simplexcited by 11
- 2024Decomposition Polyhedra of Piecewise Linear Functionscited by 9
- 2025The Computational Complexity of Counting Linear Regions in ReLU Neural Networkscited by 7
- 2023Any Deep ReLU Network is Shallowcited by 6
- 2024Representing Piecewise-Linear Functions by Functions with Minimal Aritycited by 2
- 2024Subspace Representation Learning for Sparse Linear Arrays to Localize More Sources than Sensors: A Deep Learning Methodologycited by 2
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- 2026On the Expressive Power of Transformers for Maxout Networks and Continuous Piecewise Linear Functionscited by 1
- 2026Training-Time Batch Normalization Reshapes Local Partition Geometry in Piecewise-Affine Networkscited by 1
- 2026AffineLens: Capturing the Continuous Piecewise Affine Functions of Neural Networkscited by 1
- 2026Region Seeding via Pre-Activation Regularization: A Geometric View of Piecewise Affine Neural Networkscited by 1
- 2024Two-hidden-layer ReLU neural networks and finite elementscited by 0
- 2025A Comparative Study of Invariance-Aware Loss Functions for Deep Learning-based Gridless Direction-of-Arrival Estimationcited by 0
- 2025Super-fast Rates of Convergence for Neural Network Classifiers under the Hard Margin Conditioncited by 0
- 2025Tightening the mixed integer linear formulation for the piecewise linear approximation in general dimensionscited by 0
- 2025Cellular Learning: Scattered Data Regression in High Dimensions via Voronoi Cellscited by 0
- 2025On the expressivity of sparse maxout networkscited by 0
- 2026Sparse Bayesian Learning Algorithms Revisited: From Learning Majorizers to Structured Algorithmic Learning using Neural Networkscited by 0
- 2026Regional Explanations: Bridging Local and Global Variable Importancecited by 0
- 2026A Rigorous, Tractable Measure of Model Complexitycited by 0
- 2026Expressivity Saturation: Reduced Affine Region Usage Under Increasing Task Complexitycited by 0
- 2026Expressivity Saturation: Reduced Affine Region Usage Under Increasing Task Complexity19 Jun 2026
- 2026A Rigorous, Tractable Measure of Model Complexity20 May 2026
- 2026Region Seeding via Pre-Activation Regularization: A Geometric View of Piecewise Affine Neural Networks7 May 2026
- 2026AffineLens: Capturing the Continuous Piecewise Affine Functions of Neural Networks7 May 2026
- 2026Training-Time Batch Normalization Reshapes Local Partition Geometry in Piecewise-Affine Networks6 May 2026
- 2026Regional Explanations: Bridging Local and Global Variable Importance13 Apr 2026
- 2026Sparse Bayesian Learning Algorithms Revisited: From Learning Majorizers to Structured Algorithmic Learning using Neural Networks2 Apr 2026
- 2026On the Expressive Power of Transformers for Maxout Networks and Continuous Piecewise Linear Functions3 Mar 2026
- 2025On the expressivity of sparse maxout networks15 Oct 2025
- 2025Cellular Learning: Scattered Data Regression in High Dimensions via Voronoi Cells4 Oct 2025
- 2025Tightening the mixed integer linear formulation for the piecewise linear approximation in general dimensions13 Aug 2025
- 2025The Computational Complexity of Counting Linear Regions in ReLU Neural Networks22 May 2025
14 more
- 2025Better Neural Network Expressivity: Subdividing the Simplex20 May 2025
- 2025Super-fast Rates of Convergence for Neural Network Classifiers under the Hard Margin Condition13 May 2025
- 2025A Comparative Study of Invariance-Aware Loss Functions for Deep Learning-based Gridless Direction-of-Arrival Estimation16 Mar 2025
- 2024Decomposition Polyhedra of Piecewise Linear Functions7 Oct 2024
- 2024Subspace Representation Learning for Sparse Linear Arrays to Localize More Sources than Sensors: A Deep Learning Methodology29 Aug 2024
- 2024Representing Piecewise-Linear Functions by Functions with Minimal Arity4 Jun 2024
- 2024Model Reconstruction Using Counterfactual Explanations: A Perspective From Polytope Theory8 May 2024
- 2024Two-hidden-layer ReLU neural networks and finite elements9 Mar 2024
- 2024On Minimal Depth in Neural Networks23 Feb 2024
- 2023Deep Network Approximation: Beyond ReLU to Diverse Activation Functions13 Jul 2023
- 2023Any Deep ReLU Network is Shallow20 Jun 2023
- 2023Don't trust your eyes: on the (un)reliability of feature visualizations7 Jun 2023
- 2023When Deep Learning Meets Polyhedral Theory: A Survey29 Apr 2023
- 2022Impossibility Theorems for Feature Attribution22 Dec 2022
- 2022Impossibility Theorems for Feature Attributioncited by 78
- 2023When Deep Learning Meets Polyhedral Theory: A Surveycited by 39
- 2023Deep Network Approximation: Beyond ReLU to Diverse Activation Functionscited by 33
- 2023Don't trust your eyes: on the (un)reliability of feature visualizationscited by 32
- 2024Model Reconstruction Using Counterfactual Explanations: A Perspective From Polytope Theorycited by 12
- 2024On Minimal Depth in Neural Networkscited by 11
- 2025Better Neural Network Expressivity: Subdividing the Simplexcited by 11
- 2024Decomposition Polyhedra of Piecewise Linear Functionscited by 9
- 2025The Computational Complexity of Counting Linear Regions in ReLU Neural Networkscited by 7
- 2023Any Deep ReLU Network is Shallowcited by 6
- 2024Representing Piecewise-Linear Functions by Functions with Minimal Aritycited by 2
- 2024Subspace Representation Learning for Sparse Linear Arrays to Localize More Sources than Sensors: A Deep Learning Methodologycited by 2
12 most cited of 26 All 26 (JSON)
- 2026Expressivity Saturation: Reduced Affine Region Usage Under Increasing Task Complexity19 Jun 2026
- 2026A Rigorous, Tractable Measure of Model Complexity20 May 2026
- 2026Region Seeding via Pre-Activation Regularization: A Geometric View of Piecewise Affine Neural Networks7 May 2026
- 2026AffineLens: Capturing the Continuous Piecewise Affine Functions of Neural Networks7 May 2026
- 2026Training-Time Batch Normalization Reshapes Local Partition Geometry in Piecewise-Affine Networks6 May 2026
- 2026Regional Explanations: Bridging Local and Global Variable Importance13 Apr 2026
- 2026Sparse Bayesian Learning Algorithms Revisited: From Learning Majorizers to Structured Algorithmic Learning using Neural Networks2 Apr 2026
- 2026On the Expressive Power of Transformers for Maxout Networks and Continuous Piecewise Linear Functions3 Mar 2026
- 2025On the expressivity of sparse maxout networks15 Oct 2025
- 2025Cellular Learning: Scattered Data Regression in High Dimensions via Voronoi Cells4 Oct 2025
- 2025Tightening the mixed integer linear formulation for the piecewise linear approximation in general dimensions13 Aug 2025
- 2025The Computational Complexity of Counting Linear Regions in ReLU Neural Networks22 May 2025
12 newest of 26 All 26 (JSON)