Recognition: no theorem link
φ-DeepONet: A Discontinuity Capturing Neural Operator
Pith reviewed 2026-05-10 17:54 UTC · model grok-4.3
The pith
φ-DeepONet learns mappings with discontinuities in inputs and outputs by combining multiple branch networks with a nonlinear interface embedding in the trunk, trained via physics- and interface-informed loss, and shows accurate results on 1D/2D benchmarks.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We evaluate φ-DeepONet on several one- and two-dimensional benchmark problems and demonstrate that it delivers accurate and stable predictions even in the presence of strong interface-driven discontinuities.
Load-bearing premise
That a nonlinear latent embedding built from a one-hot representation of domain decomposition, when combined with spatial coordinates in the trunk, is sufficient to capture and propagate strong and weak discontinuities in the output fields.
Figures
read the original abstract
We present $\phi-$DeepONet, a physics-informed neural operator designed to learn mappings between function spaces that may contain discontinuities or exhibit non-smooth behavior. Classical neural operators are based on the universal approximation theorem which assumes that both the operator and the functions it acts on are continuous. However, many scientific and engineering problems involve naturally discontinuous input fields as well as strong and weak discontinuities in the output fields caused by material interfaces. In $\phi$-DeepONet, discontinuities in the input are handled using multiple branch networks, while discontinuities in the output are learned through a nonlinear latent embedding of the interface. This embedding is constructed from a {\it one-hot} representation of the domain decomposition that is combined with the spatial coordinates in a modified trunk network. The outputs of the branch and trunk networks are then combined through a dot product to produce the final solution, which is trained using a physics- and interface-informed loss function. We evaluate $\phi$-DeepONet on several one- and two-dimensional benchmark problems and demonstrate that it delivers accurate and stable predictions even in the presence of strong interface-driven discontinuities.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces φ-DeepONet, a physics-informed neural operator extending DeepONet to handle discontinuities. Input discontinuities are addressed via multiple branch networks, while output discontinuities are captured through a nonlinear latent embedding constructed from a one-hot representation of the domain decomposition, which is concatenated with spatial coordinates in a modified trunk network. Branch and trunk outputs are combined via dot product, and the model is trained with a physics- and interface-informed loss. The authors evaluate the method on several 1D and 2D benchmark problems and claim it delivers accurate and stable predictions even with strong interface-driven discontinuities.
Significance. If the quantitative claims hold, the work would address a known limitation of standard neural operators (which rely on continuity assumptions) and could be useful for interface problems in computational mechanics and engineering. The explicit incorporation of domain decomposition into the trunk and the physics-informed loss represent a concrete architectural attempt to capture discontinuities without post-processing. However, the approach's dependence on a priori known interfaces reduces its generality relative to fully data-driven alternatives.
major comments (2)
- [Abstract / Method] Abstract and method description: the architecture presupposes that the domain decomposition (and thus the one-hot interface labels) is known exactly when evaluating the operator. This is a load-bearing assumption for the central claim of a general 'discontinuity capturing neural operator,' yet the manuscript provides no mechanism for learning or tolerating uncertainty in interface locations. Benchmarks may succeed only because the decomposition is supplied as part of the problem setup; without this, the nonlinear latent embedding cannot be constructed.
- [Abstract] Abstract: the claim that 'benchmark tests produced accurate stable results' is stated without any quantitative metrics, baseline comparisons (e.g., standard DeepONet or PINN variants), error bars, or details on how the physics- and interface-informed loss is constructed (e.g., weighting of interface terms or enforcement of jump conditions). This leaves the performance assertions weakly supported and prevents assessment of whether the method improves upon existing approaches.
minor comments (1)
- [Abstract] Notation: the symbol φ is used in the title and abstract but its precise definition (as the nonlinear embedding or the full operator) is not clarified early in the text, which may confuse readers familiar with standard DeepONet notation.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback on our manuscript. We address each major comment below and have prepared revisions to clarify assumptions and strengthen the presentation of results.
read point-by-point responses
-
Referee: [Abstract / Method] Abstract and method description: the architecture presupposes that the domain decomposition (and thus the one-hot interface labels) is known exactly when evaluating the operator. This is a load-bearing assumption for the central claim of a general 'discontinuity capturing neural operator,' yet the manuscript provides no mechanism for learning or tolerating uncertainty in interface locations. Benchmarks may succeed only because the decomposition is supplied as part of the problem setup; without this, the nonlinear latent embedding cannot be constructed.
Authors: We acknowledge that φ-DeepONet requires a priori knowledge of the domain decomposition to construct the one-hot representation and nonlinear latent embedding. This design choice targets interface problems in which material or geometric interfaces are known exactly, as is standard in many computational mechanics settings. The method does not incorporate mechanisms to infer or tolerate uncertainty in interface locations, which would necessitate a separate interface-detection component. We will revise the abstract and Section 2 to explicitly state this assumption and reframe the contribution as a discontinuity-capturing operator for known-interface problems rather than a fully general unknown-discontinuity solver. This clarification does not alter the reported numerical results but improves the scope statement. revision: yes
-
Referee: [Abstract] Abstract: the claim that 'benchmark tests produced accurate stable results' is stated without any quantitative metrics, baseline comparisons (e.g., standard DeepONet or PINN variants), error bars, or details on how the physics- and interface-informed loss is constructed (e.g., weighting of interface terms or enforcement of jump conditions). This leaves the performance assertions weakly supported and prevents assessment of whether the method improves upon existing approaches.
Authors: The abstract is intentionally concise, but the full manuscript (Section 4) reports quantitative L2 errors, direct comparisons against standard DeepONet on the same benchmarks, error bars obtained from multiple independent runs, and the explicit form of the physics- and interface-informed loss (including weighting coefficients for interface residual terms and enforcement of jump conditions). To address the concern, we will augment the abstract with representative quantitative metrics and a brief reference to the loss construction. These additions will be drawn directly from the existing numerical results without introducing new experiments. revision: yes
Circularity Check
No significant circularity; architectural claims rest on explicit design and benchmarks.
full rationale
The paper presents φ-DeepONet as an architectural extension of DeepONet that uses multiple branch networks for discontinuous inputs and a nonlinear latent embedding constructed from a one-hot domain decomposition concatenated into a modified trunk network, with training via a physics- and interface-informed loss. No equations or results in the provided description reduce the claimed predictions or performance to quantities defined by the same fitted parameters, self-citations, or ansatzes imported from prior author work. The central claims are supported by direct evaluation on one- and two-dimensional benchmark problems rather than any derivation that loops back to its inputs by construction. This is the normal case of a self-contained methodological contribution.
Axiom & Free-Parameter Ledger
free parameters (1)
- network architecture hyperparameters
axioms (1)
- domain assumption The modified trunk with one-hot interface embedding can represent strong and weak discontinuities when combined with the branch outputs via dot product.
invented entities (1)
-
nonlinear latent embedding of the interface
no independent evidence
Forward citations
Cited by 1 Pith paper
-
Shock-Centered Low-Rank Structure and Neural-Operator Representation of Rarefied Micro-Nozzle Flows
Shock-centered scaling of DSMC fields in micro-nozzles reveals low-rank density structure, enabling DeepONet surrogates with mean errors reduced to 4.51% on hardest test cases.
Reference graph
Works this paper leans on
-
[1]
Heat conduction in layered, composite materials.Journal of applied physics, 57(5):1569–1573, 1985
James Baker-Jarvis and Ramarao Inguva. Heat conduction in layered, composite materials.Journal of applied physics, 57(5):1569–1573, 1985
1985
-
[2]
Heat transfer analysis in multi-layered materials with interfacial thermal resistance.Composite Structures, 293:115728, 2022
Wei-bin Yuan, Nanting Yu, Long-yuan Li, and Yuan Fang. Heat transfer analysis in multi-layered materials with interfacial thermal resistance.Composite Structures, 293:115728, 2022
2022
-
[3]
Evaluation of the moisture effect on the material interface using multiscale modeling.Multiscale Science and Engineering, 1(2):108–118, 2019
Renyuan Qin and Denvid Lau. Evaluation of the moisture effect on the material interface using multiscale modeling.Multiscale Science and Engineering, 1(2):108–118, 2019
2019
-
[4]
Multi-material modeling of sorption-desorption processes with experimental validation.Chemical Engineering Science, 253:117542, 2022
Pratanu Roy, Stephen T Castonguay, Jennifer M Knipe, Yunwei Sun, Elizabeth A Glascoe, and Hom N Sharma. Multi-material modeling of sorption-desorption processes with experimental validation.Chemical Engineering Science, 253:117542, 2022
2022
-
[5]
Robert J Fisher and Robert A Peattie. Controlling tissue microenvironments: biomimetics, transport phenomena, and reacting systems.Tissue Engineering II: Basics of Tissue Engineering and Tissue Applications, pages 1–73, 2006
2006
-
[6]
Modeling fluid flow in fractured porous media with the interfacial conditions between porous medium and fracture.Transport in Porous Media, 139(1):109–129, 2021
N Hosseini and AR Khoei. Modeling fluid flow in fractured porous media with the interfacial conditions between porous medium and fracture.Transport in Porous Media, 139(1):109–129, 2021
2021
-
[7]
A finite element method for interface problems in domains with smooth boundaries and interfaces.Advances in Computational Mathematics, 6(1):109–138, 1996
James H Bramble and J Thomas King. A finite element method for interface problems in domains with smooth boundaries and interfaces.Advances in Computational Mathematics, 6(1):109–138, 1996
1996
-
[8]
A locally modified parametric finite element method for interface problems
Stefan Frei and Thomas Richter. A locally modified parametric finite element method for interface problems. SIAM Journal on Numerical Analysis, 52(5):2315–2334, 2014
2014
-
[9]
Grid modification during simulated fracture propagation, March 21 2023
Dakshina M Valiveti, Chandrasekhar A Srinivas, and Vadim Dyadechko. Grid modification during simulated fracture propagation, March 21 2023. US Patent 11,608,730
2023
-
[10]
An efficient finite element method for embedded interface problems.International journal for numerical methods in engineering, 78(2):229–252, 2009
John Dolbow and Isaac Harari. An efficient finite element method for embedded interface problems.International journal for numerical methods in engineering, 78(2):229–252, 2009
2009
-
[11]
Physics- informed machine learning.Nature Reviews Physics, 3(6):422–440, 2021
George Em Karniadakis, Ioannis G Kevrekidis, Lu Lu, Paris Perdikaris, Sifan Wang, and Liu Yang. Physics- informed machine learning.Nature Reviews Physics, 3(6):422–440, 2021
2021
-
[12]
Maziar Raissi, Paris Perdikaris, and George E Karniadakis. Physics-informed neural networks: A deep learning framework for solving forward and inverse problems involving nonlinear partial differential equations.Journal of Computational physics, 378:686–707, 2019
2019
-
[13]
Multilayer feedforward networks are universal approxi- mators.Neural networks, 2(5):359–366, 1989
Kurt Hornik, Maxwell Stinchcombe, and Halbert White. Multilayer feedforward networks are universal approxi- mators.Neural networks, 2(5):359–366, 1989
1989
-
[14]
Physics-informed neural networks (pinns) for fluid mechanics: A review.Acta Mechanica Sinica, 37(12):1727–1738, 2021
Shengze Cai, Zhiping Mao, Zhicheng Wang, Minglang Yin, and George Em Karniadakis. Physics-informed neural networks (pinns) for fluid mechanics: A review.Acta Mechanica Sinica, 37(12):1727–1738, 2021
2021
-
[15]
Scientific machine learning through physics–informed neural networks: Where we are and what’s next
Salvatore Cuomo, Vincenzo Schiano Di Cola, Fabio Giampaolo, Gianluigi Rozza, Maziar Raissi, and Francesco Piccialli. Scientific machine learning through physics–informed neural networks: Where we are and what’s next. Journal of Scientific Computing, 92(3):88, 2022
2022
-
[16]
Understanding physics-informed neural networks: Tech- niques, applications, trends, and challenges.AI, 5(3):1534–1557, 2024
Amer Farea, Olli Yli-Harja, and Frank Emmert-Streib. Understanding physics-informed neural networks: Tech- niques, applications, trends, and challenges.AI, 5(3):1534–1557, 2024
2024
-
[17]
Neural operator: Learning maps between function spaces with applications to pdes.Journal of Machine Learning Research, 24(89):1–97, 2023
Nikola Kovachki, Zongyi Li, Burigede Liu, Kamyar Azizzadenesheli, Kaushik Bhattacharya, Andrew Stuart, and Anima Anandkumar. Neural operator: Learning maps between function spaces with applications to pdes.Journal of Machine Learning Research, 24(89):1–97, 2023
2023
-
[18]
Neural operators for accelerating scientific simulations and design.Nature Reviews Physics, 6(5):320–328, 2024
Kamyar Azizzadenesheli, Nikola Kovachki, Zongyi Li, Miguel Liu-Schiaffini, Jean Kossaifi, and Anima Anand- kumar. Neural operators for accelerating scientific simulations and design.Nature Reviews Physics, 6(5):320–328, 2024. 22 APREPRINT- APRIL10, 2026
2024
-
[19]
Learning nonlinear operators via deeponet based on the universal approximation theorem of operators.Nature machine intelligence, 3(3): 218–229, 2021
Lu Lu, Pengzhan Jin, Guofei Pang, Zhongqiang Zhang, and George Em Karniadakis. Learning nonlinear operators via deeponet based on the universal approximation theorem of operators.Nature machine intelligence, 3(3): 218–229, 2021
2021
-
[20]
Tianping Chen and Hong Chen. Universal approximation to nonlinear operators by neural networks with arbitrary activation functions and its application to dynamical systems.IEEE transactions on neural networks, 6(4): 911–917, 1995
1995
-
[21]
A comprehensive and fair comparison of two neural operators (with practical extensions) based on fair data.Computer Methods in Applied Mechanics and Engineering, 393:114778, 2022
Lu Lu, Xuhui Meng, Shengze Cai, Zhiping Mao, Somdatta Goswami, Zhongqiang Zhang, and George Em Karniadakis. A comprehensive and fair comparison of two neural operators (with practical extensions) based on fair data.Computer Methods in Applied Mechanics and Engineering, 393:114778, 2022
2022
-
[22]
Fourier Neural Operator for Parametric Partial Differential Equations
Zongyi Li, Nikola Kovachki, Kamyar Azizzadenesheli, Burigede Liu, Kaushik Bhattacharya, Andrew Stuart, and Anima Anandkumar. Fourier neural operator for parametric partial differential equations.arXiv preprint arXiv:2010.08895, 2020
work page internal anchor Pith review arXiv 2010
-
[23]
arXiv preprint arXiv:2205.02191 , year=
Tapas Tripura and Souvik Chakraborty. Wavelet neural operator: a neural operator for parametric partial differential equations.arXiv preprint arXiv:2205.02191, 2022
-
[24]
Katiana Kontolati, Somdatta Goswami, George Em Karniadakis, and Michael D Shields. Learning in latent spaces improves the predictive accuracy of deep neural operators.arXiv preprint arXiv:2304.07599, 2023
-
[25]
Extended physics-informed neural networks (xpinns): A generalized space-time domain decomposition based deep learning framework for nonlinear partial differential equations
Ameya D Jagtap and George Em Karniadakis. Extended physics-informed neural networks (xpinns): A generalized space-time domain decomposition based deep learning framework for nonlinear partial differential equations. Communications in Computational Physics, 28(5), 2020
2020
-
[26]
Multi-domain physics-informed neural network for solving forward and inverse problems of steady-state heat conduction in multilayer media.Physics of Fluids, 34(11), 2022
Benrong Zhang, Guozheng Wu, Yan Gu, Xiao Wang, and Fajie Wang. Multi-domain physics-informed neural network for solving forward and inverse problems of steady-state heat conduction in multilayer media.Physics of Fluids, 34(11), 2022
2022
-
[27]
Interface pinns (i-pinns): A physics-informed neural networks framework for interface problems.Computer Methods in Applied Mechanics and Engineering, 429:117135, 2024
Antareep Kumar Sarma, Sumanta Roy, Chandrasekhar Annavarapu, Pratanu Roy, and Shriram Jagannathan. Interface pinns (i-pinns): A physics-informed neural networks framework for interface problems.Computer Methods in Applied Mechanics and Engineering, 429:117135, 2024
2024
-
[28]
Adaptive interface-pinns (adai- pinns): An efficient physics-informed neural networks framework for interface problems.Communications in Computational Physics, 37(3):603–622, 2025
Sumanta Roy, Chandrasekhar Annavarapu, Antareep Kumar Sarma, et al. Adaptive interface-pinns (adai- pinns): An efficient physics-informed neural networks framework for interface problems.Communications in Computational Physics, 37(3):603–622, 2025
2025
-
[29]
Jiachun Zheng, Yunqing Huang, and Nianyu Yi. Ae-pinns: Attention-enhanced physics-informed neural networks for solving elliptic interface problems.arXiv preprint arXiv:2506.18332, 2025
-
[30]
Hg-pinn: A residual physics-informed neural network framework for heterogeneous groundwater flow simulation.Desalination and Water Treatment, page 101577, 2025
Zhang Yuan, Yongxia Wu, and Chenyu Sun. Hg-pinn: A residual physics-informed neural network framework for heterogeneous groundwater flow simulation.Desalination and Water Treatment, page 101577, 2025
2025
-
[31]
wbpinn: Weight balanced physics-informed neural networks for multi-objective learning.Applied Soft Computing, 170:112632, 2025
Fujun Cao, Xiaobin Guo, Xinzheng Dong, and Dongfang Yuan. wbpinn: Weight balanced physics-informed neural networks for multi-objective learning.Applied Soft Computing, 170:112632, 2025
2025
-
[32]
Ig-pinns: Interface-gated physics-informed neural networks for solving elliptic interface problems.Journal of Computational Physics, page 114540, 2025
Jiachun Zheng, Yunqing Huang, and Nianyu Yi. Ig-pinns: Interface-gated physics-informed neural networks for solving elliptic interface problems.Journal of Computational Physics, page 114540, 2025
2025
-
[33]
A discontinuity capturing shallow neural network for elliptic interface problems.Journal of Computational Physics, 469:111576, 2022
Wei-Fan Hu, Te-Sheng Lin, and Ming-Chih Lai. A discontinuity capturing shallow neural network for elliptic interface problems.Journal of Computational Physics, 469:111576, 2022
2022
-
[34]
Wei-Fan Hu, Te-Sheng Lin, and Ming-Chih Lai. A discontinuity-capturing neural network with categorical embedding and its application to anisotropic elliptic interface problems.arXiv preprint arXiv:2503.15441, 2025
-
[35]
Solving parametric elliptic interface problems via interfaced operator network.Journal of Computational Physics, 514:113217, 2024
Sidi Wu, Aiqing Zhu, Yifa Tang, and Benzhuo Lu. Solving parametric elliptic interface problems via interfaced operator network.Journal of Computational Physics, 514:113217, 2024
2024
-
[36]
Ting Du, Xianliang Xu, Wang Kong, Ye Li, and Zhongyi Huang. Physics-informed tailored finite point operator network for parametric interface problems.arXiv preprint arXiv:2409.10284, 2024
-
[37]
Mionet: Learning multiple-input operators via tensor product.SIAM Journal on Scientific Computing, 44(6):A3490–A3514, 2022
Pengzhan Jin, Shuai Meng, and Lu Lu. Mionet: Learning multiple-input operators via tensor product.SIAM Journal on Scientific Computing, 44(6):A3490–A3514, 2022
2022
-
[38]
arXiv preprint arXiv:1604.06737 , year=
Cheng Guo and Felix Berkhahn. Entity embeddings of categorical variables.arXiv preprint arXiv:1604.06737, 2016
-
[39]
Exact imposition of boundary conditions with distance functions in physics-informed deep neural networks.Computer Methods in Applied Mechanics and Engineering, 389:114333, 2022
Natarajan Sukumar and Ankit Srivastava. Exact imposition of boundary conditions with distance functions in physics-informed deep neural networks.Computer Methods in Applied Mechanics and Engineering, 389:114333, 2022. 23 APREPRINT- APRIL10, 2026
2022
-
[40]
Adam: A Method for Stochastic Optimization
Diederik P. Kingma and Jimmy Ba. Adam: A method for stochastic optimization, 2017. URLhttps://arxiv. org/abs/1412.6980
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[41]
SOAP: Improving and Stabilizing Shampoo using Adam
Nikhil Vyas, Depen Morwani, Rosie Zhao, Mujin Kwun, Itai Shapira, David Brandfonbrener, Lucas Janson, and Sham Kakade. Soap: Improving and stabilizing shampoo using adam.arXiv preprint arXiv:2409.11321, 2024
work page internal anchor Pith review arXiv 2024
-
[42]
Understanding the difficulty of training deep feedforward neural networks
Xavier Glorot and Yoshua Bengio. Understanding the difficulty of training deep feedforward neural networks. InProceedings of the thirteenth international conference on artificial intelligence and statistics, pages 249–256. JMLR Workshop and Conference Proceedings, 2010
2010
-
[43]
Simon and Schuster, 2024
Grigory Sapunov.Deep learning with JAX. Simon and Schuster, 2024
2024
-
[44]
Learning the solution operator of parametric partial differential equations with physics-informed deeponets.Science advances, 7(40):eabi8605, 2021
Sifan Wang, Hanwen Wang, and Paris Perdikaris. Learning the solution operator of parametric partial differential equations with physics-informed deeponets.Science advances, 7(40):eabi8605, 2021
2021
-
[45]
Application of the finite-element method to the diffusion and reaction of chemical species in multilayered polymeric bodies.Mathematical Modelling, 7(2-3):385–395, 1986
DT Wadiak. Application of the finite-element method to the diffusion and reaction of chemical species in multilayered polymeric bodies.Mathematical Modelling, 7(2-3):385–395, 1986
1986
-
[46]
Modeling diffusion and types iv sorption of water vapor in heterogeneous systems.Chemical Engineering Science, 275:118695, 2023
Stephen T Castonguay, Pratanu Roy, Yunwei Sun, Sylvie Aubry, Brandon Foley, Elizabeth A Glascoe, and Hom N Sharma. Modeling diffusion and types iv sorption of water vapor in heterogeneous systems.Chemical Engineering Science, 275:118695, 2023. 24
2023
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.