# On the Finite-Time Complexity and Practical Computation of Approximate Stationarity Concepts of Lipschitz Functions

arXiv: https://arxiv.org/abs/2112.09002 · HTML: https://mlsanity.com/paper/2112.09002/

## Key facts

- Cited by 31 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 16 Dec 2021.

## Built on by (most cited first, 30 of 31)

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- [Testing Stationarity Concepts for ReLU Networks: Hardness, Regularity, and Robust Algorithms](https://mlsanity.com/paper/2302.12261/) (2023)
- [The Convergence Behavior of Adam under Heavy-Tailed Noise](https://mlsanity.com/paper/2607.27383/) (2026)
- [Musec: MomentUm SpEctral Clipping for Stable Muon-type Training](https://mlsanity.com/paper/2609.11655/) (2026)
- [Perturbed Iterate SGD for Lipschitz Continuous Loss Functions with Numerical Error and Adaptive Step Sizes](https://mlsanity.com/paper/2211.04655/) (2022)
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- [On the Hardness of Meaningful Local Guarantees in Nonsmooth Nonconvex Optimization](https://mlsanity.com/paper/2409.10323/) (2024)
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- [The Hidden Power of Normalization Layers in Neural Networks: Exponential Capacity Control](https://mlsanity.com/paper/2511.00958/) (2025)
- [Stability and Generalization of Stochastic Nonconvex Optimization under Heavy-Tailed Noise: From Gradient Norm to Goldstein Stationarity](https://mlsanity.com/paper/2601.19730/) (2026)
- [Parameterized Complexity of Stationarity Testing for Piecewise-Affine Functions and Shallow CNN Losses](https://mlsanity.com/paper/2605.10219/) (2026)
- [Zeroth-Order Nonconvex Nonsmooth Optimization with Heavy-Tailed Noise](https://mlsanity.com/paper/2605.24513/) (2026)
- [Adam Converges in Nonsmooth Nonconvex Optimization](https://mlsanity.com/paper/2606.22326/) (2026)
- [Optimizing the Preconditioner: A Black-box Online-to-Nonconvex Conversion with Static Regret Minimization Oracles](https://mlsanity.com/paper/2607.17607/) (2026)
- [The Exponential Price of Determinism in Nonsmooth Nonconvex Optimization](https://mlsanity.com/paper/2609.23837/) (2026)

## Abstract (arXiv)

We report a practical finite-time algorithmic scheme to compute approximately stationary points for nonconvex nonsmooth Lipschitz functions. In particular, we are interested in two kinds of approximate stationarity notions for nonconvex nonsmooth problems, i.e., Goldstein approximate stationarity (GAS) and near-approximate stationarity (NAS). For GAS, our scheme removes the unrealistic subgradient selection oracle assumption in (Zhang et al., 2020, Assumption 1) and computes GAS with the same finite-time complexity. For NAS, Davis & Drusvyatskiy (2019) showed that ρ-weakly convex functions admit finite-time computation, while Tian & So (2021) provided the matching impossibility results of dimension-free finite-time complexity for first-order methods. Complement to these developments, in this paper, we isolate a new class of functions that could be Clarke irregular (and thus not weakly convex anymore) and show that our new algorithmic scheme can compute NAS points for functions in that class within finite time. To demonstrate the wide applicability of our new theoretical framework, we show that ρ-margin SVM, 1-layer, and 2-layer ReLU neural networks, all being Clarke irregular, satisfy our new conditions.