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arXiv research

A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

168,657 papers · 148 categories

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4080119159 · May 202619922001200920172026
48 results for Depth Separation

New findings on depth vs. width in neural networks, showing depth can improve learnability.

problem Understanding the role of depth in neural networks, especially when width is unbounded.
method Analyzing sample complexity for learnability in norm-controlled depth-2 and depth-3 ReLU networks.
result Depth can improve learnability of functions that are otherwise unlearnable with depth-2 networks.

Proves depth 2 neural networks can't approximate certain functions as well as depth 3 networks.

problem Approximating functions with depth 2 networks in high dimensions.
method Lower bound proof using worst-to-average-case random self-reducibility.
result Proves depth 2 networks can't approximate certain functions as well as depth 3 networks, resolving an open problem.

Study on size and depth of neural networks for approximating benign functions, showing barriers and explicit results.

problem Understanding how size and depth of neural networks affect their ability to approximate benign functions.
method Analyzing ReLU networks for benign functions, proving barriers and explicit results.
result Explicit benign functions that cannot be approximated by networks of certain sizes or depths, showing barriers to size and depth separation.

Existing depth separation results for constant-depth networks essentially show that certain radial functions in Rd\mathbb{R}^d, which can be easily approximated with depth 33 networks, cannot be approximated by depth 22 networks, even up to constant accuracy, unless their size is exponential in dd. However, the func…

2019-04-15abs ↗pdf ↗

Study shows depth improves generalization in deep learning models.

problem Understanding why and when depth improves generalization in deep learning.
method Implementation-agnostic state-transition model to analyze depth and generalization.
result Identifies geometric and semigroup mechanisms that keep entropy contribution saturated or polynomial, clarifying depth's statistical advantage.

Transformers can learn noisy linear systems with depth and IID data.

problem Learning noisy linear dynamical systems with transformers.
method Theoretical analysis of multi-layer and single-layer transformers with respect to L2L^2-testing loss.
result Single-layer transformers have a non-diminishing lower bound on approximation error, suggesting depth separation.

The paper proves barriers to approximating functions with small weights and depth in neural networks.

problem Proving barriers to approximating functions with constant depth neural networks.
method Reduction to open problems and natural-proof barriers in circuit complexity, and a new approach to polynomially-bounded functions.
result There are fundamental barriers to proving results beyond depth 4 for constant-depth neural networks.

This paper extends depth separation results to piece-wise oscillatory functions.

problem Approximating functions with piece-wise oscillatory structure using neural networks.
method Extends existing results to piece-wise oscillatory functions using proof strategy from (Eldan and Shamir, 2016).
result Approximation by one-hidden-layer networks holds at a poly(d) rate for functions with constant domain radius and oscillation rate.

Let f:Sd1×Sd1Sf:\mathbb{S}^{d-1}\times \mathbb{S}^{d-1}\to\mathbb{S} be a function of the form f(x,x)=g(x,x)f(\mathbf{x},\mathbf{x}') = g(\langle\mathbf{x},\mathbf{x}'\rangle) for g:[1,1]Rg:[-1,1]\to \mathbb{R}. We give a simple proof that shows that poly-size depth two neural networks with (exponentially) bounded weights cannot approximate $f…

2017-02-27abs ↗pdf ↗

New algorithm quantifies uncertainty in regression models for complex data types.

problem Uncertainty quantification in regression models for complex data types.
method Model-free uncertainty quantification algorithm based on conditional depth measures and kernel mean embeddings.
result Provides faster convergence rates and non-asymptotic guarantees for prediction regions.

Poly-GNNs achieve similar performance regardless of depth, highlighting graph noise's dominance.

problem Performance of poly-GNNs in semi-supervised node classification.
method Analysis of poly-GNNs under a contextual stochastic block model (CSBM).
result For a sufficiently large graph, depth k>1k > 1 poly-GNNs exhibit the same rate of separation as depth k=1k=1 counterparts.

This paper explains a mechanism called phase collapse that improves image classification accuracy.

problem Understanding the role of non-linearities and convolutional filters in image classification.
method Demonstrates phase collapse as a mechanism that eliminates spatial variability and linearly separates classes.
result Phase collapse improves classification accuracy, while thresholding operators degrade performance.

Deep RNNs excel at capturing long-term dependencies in sequential data.

problem Lack of a formal measure for RNNs' long-term memory capacity.
method Introduced a measure called Start-End separation rank to quantify RNNs' ability to model long-term dependencies.
result Deep RNNs support Start-End separation ranks that are combinatorially higher than shallow ones.

Following the seminal idea of Tukey, data depth is a function that measures how close an arbitrary point of the space is located to an implicitly defined center of a data cloud. Having undergone theoretical and computational developments, it is now employed in numerous applications with classification being the most po…

2016-08-14abs ↗pdf ↗

This work establishes universality for deep equivariant networks, overcoming limitations of previous approaches.

problem Rarity of universality results for equivariant neural networks, especially in high-dimensional settings.
method Develops a more general account of universality for equivariant networks, introducing entry-wise separability and readout layers.
result Deep equivariant networks achieve universality under entry-wise separability, with or without readout layers.

Study on feature learning dynamics in infinite-depth neural networks, focusing on ResNets.

problem Understanding how features evolve during training in deep neural networks, especially in the large-depth limit.
method Conditional Gaussian representations and SDE system with decoupled backward weights.
result Depth-induced suppression of forward-backward coupling in infinite-depth networks, leading to a decoupled forward-backward SDE system.

We develop a scalable method for Bayesian neural networks with stochastic differential equations.

problem Uncertainty quantification in deep neural networks.
method Gradient-based stochastic variational inference in continuous-depth Bayesian neural networks.
result Gradient estimator with zero variance as the approximation improves.

This work briefly explores the possibility of approximating spatial distance (alternatively, similarity) between data points using the Isolation Forest method envisioned for outlier detection. The logic is similar to that of isolation: the more similar or closer two points are, the more random splits it will take to se…

2019-10-27abs ↗pdf ↗

This paper explores how neural network width and depth behave as they approach infinity.

problem Understanding the behavior of neural functions as width and depth go to infinity.
method Formal definition of commutativity framework, study of neural covariance kernel, novel proof techniques.
result Taking width and depth to infinity in a deep neural network with skip connections results in the same covariance structure, regardless of the order of taking limits.

Deep networks can perfectly classify two low-dimensional manifolds on a sphere with large depth and width.

problem Binary classification of two low-dimensional submanifolds on a sphere.
method Analysis of a deep fully-connected neural network trained to separate two submanifolds of the unit sphere.
result Randomly-initialized gradient descent can perfectly classify the two manifolds with high probability when the network depth is large relative to certain geometric and statistical properties of the data.

Deep networks can learn functions approximated by shallow networks, but not all functions.

problem The learnability of functions by deep neural networks and the approximation capacity of simpler classes.
method Study the connection between learnability and approximation capacity of functions by deep neural networks and simpler classes.
result A necessary condition for a function to be learnable by deep neural networks is to be approximable by shallow networks.

Study reveals how depth of reasoning affects generalization in models.

problem Understanding scaling behavior of generalization with CoT depth.
method Theoretical model of CoT in linear regression using random matrix theory.
result Sharp phase transition between exponential and polynomial improvement, saturation, and overthinking.

This paper optimizes ReLU networks for approximating Hölder continuous functions.

problem Optimizing the approximation rate of ReLU networks in terms of width and depth.
method Constructive proof of ReLU networks' approximation power with specific width and depth constraints.
result Optimal approximation rate of ReLU networks with width and depth constraints.

For any positive integer kk, there exist neural networks with Θ(k3)Θ(k^3) layers, Θ(1)Θ(1) nodes per layer, and Θ(1)Θ(1) distinct parameters which can not be approximated by networks with O(k)\mathcal{O}(k) layers unless they are exponentially large --- they must possess Ω(2k)Ω(2^k) nodes. This result is proved here for a class o…

2016-02-14abs ↗pdf ↗

Neural network models are resource hungry. It is difficult to deploy such deep networks on devices with limited resources, like smart wearables, cellphones, drones, and autonomous vehicles. Low bit quantization such as binary and ternary quantization is a common approach to alleviate this resource requirements. Ternary…

2019-09-26abs ↗pdf ↗

We study the approximation properties of random ReLU features through their reproducing kernel Hilbert space (RKHS). We first prove a universality theorem for the RKHS induced by random features whose feature maps are of the form of nodes in neural networks. The universality result implies that the random ReLU features…

2018-10-10abs ↗pdf ↗

Optimal ReLU networks can memorize any separable set of points with a small number of parameters.

problem The optimal number of parameters required to memorize a set of points using ReLU networks.
method Construction of ReLU networks with specific bit complexity to memorize points satisfying a mild separability assumption.
result Optimal ReLU networks can memorize any separable set of points with a number of parameters that is ildeO(N) ilde{O}(\sqrt{N}).

Theory explains deep nonlinear networks' plateaus and transitions.

problem Understanding long plateaus and feature acquisition transitions in deep nonlinear networks.
method Derived an exact identity for Frobenius norms, classified activation functions, and reduced matrix flow to a scalar ODE.
result Escape time law τ=Θ(ε(r2))τ_\star = Θ(\varepsilon^{-(r-2)}) for deep nonlinear networks, where rr is the number of bottleneck layers.

Generates infinite-depth hierarchical clusters from few examples.

problem Inadequate finite-sample clustering methods for fine-scale hierarchical structures.
method Classification fields generated by a local refinement rule, approximated by predictors.
result Learned predictors can approximate infinite-depth hierarchical structures.

Understanding the power of depth in feed-forward neural networks is an ongoing challenge in the field of deep learning theory. While current works account for the importance of depth for the expressive power of neural-networks, it remains an open question whether these benefits are exploited during a gradient-based opt…

2019-03-08abs ↗pdf ↗

A new statistical concept, lepto-variance, is defined for stock returns using Regression Trees.

problem Understanding the underlying structure of stock returns using statistical methods.
method Defining lepto-variance as the variance that cannot be removed by any regression tree of a specific depth and analyzing stock returns with 1- and 2-bit Regression Trees.
result Lepto-variance quantifies the resolving power of Regression Trees for stock returns, decomposing total variance into lepto-variance and macro-variance.

Non-negative matrix factorization is a problem of dimensionality reduction and source separation of data that has been widely used in many fields since it was studied in depth in 1999 by Lee and Seung, including in compression of data, document clustering, processing of audio spectrograms and astronomy. In this work we…

2019-10-31abs ↗pdf ↗

Independent component analysis (ICA) has been widely used for blind source separation in many fields such as brain imaging analysis, signal processing and telecommunication. Many statistical techniques based on M-estimates have been proposed for estimating the mixing matrix. Recently, several nonparametric methods have…

2007-05-29abs ↗pdf ↗

New bounds improve graph node classification using optimal transport.

problem Improving transductive generalization bounds for graph node classification.
method Representation-based generalization bounds via optimal transport, expressed in terms of Wasserstein distances.
result Strong correlation between derived bounds and empirical generalization in graph node classification.

While on some natural distributions, neural-networks are trained efficiently using gradient-based algorithms, it is known that learning them is computationally hard in the worst-case. To separate hard from easy to learn distributions, we observe the property of local correlation: correlation between local patterns of t…

2019-10-25abs ↗pdf ↗

Enhanced ODT with Feature Concatenation boosts learning efficiency.

problem Insufficient learning efficiency of ODT due to linear projections not being transmitted to child nodes.
method Feature Concatenation ( exttt{FC-ODT}) to transmit linear projections along decision paths.
result Experiments show exttt{FC-ODT} outperforms state-of-the-art decision trees with a limited tree depth.