Recognition: unknown
Physics-Informed Neural Networks for Solving Derivative-Constrained PDEs
Pith reviewed 2026-05-10 13:08 UTC · model grok-4.3
The pith
Derivative-constrained PINNs embed bounds and monotonicity directly into the optimization to produce physically admissible PDE solutions.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
DC-PINNs treat constrained PDE solving as an optimization guided by a minimum objective function criterion in which the physics resides in the minimum principle; they embed general nonlinear constraints on states and derivatives via automatic differentiation and employ self-adaptive loss balancing to tune each term, consistently reducing constraint violations and improving physical fidelity versus baseline PINN variants on heat diffusion with bounds, financial volatilities with arbitrage-free conditions, and fluid flow with shed vortices.
What carries the argument
The minimum objective function criterion that incorporates both PDE residual and derivative constraints, computed via automatic differentiation and balanced by self-adaptive loss weighting.
If this is right
- Solutions satisfy hard derivative constraints such as bounds, monotonicity, convexity, and incompressibility even when the PDE residual alone would allow violations.
- Training remains stable on problems where the PDE residual is small but the constraints are active.
- Self-adaptive balancing reduces the need for manual hyperparameter tuning and problem-specific network designs.
- The same framework applies across heat, financial, and fluid-flow examples without changing the core architecture.
Where Pith is reading between the lines
- The approach could be tested on time-dependent or high-dimensional PDEs where derivative constraints become especially costly to enforce by other means.
- Combining the minimum-principle formulation with uncertainty quantification might reveal how constraint adherence affects solution reliability.
- The method might extend naturally to hybrid physics-ML models that include both neural and traditional discretizations.
Load-bearing premise
The minimum objective function criterion with self-adaptive loss balancing correctly captures the desired physical behavior without introducing new instabilities or hidden biases.
What would settle it
A benchmark run in which DC-PINNs produce larger derivative-constraint violations or less stable training than standard PINNs when the same PDE residual is achieved.
Figures
read the original abstract
Physics-Informed Neural Networks (PINNs) recast PDE solving as an optimisation problem in function space by minimising a residual-based objective, yet many applications require additional derivative-based relations that are just as fundamental as the governing equations. In this paper, we present Derivative-Constrained PINNs (DC-PINNs), a general framework that treats constrained PDE solving as an optimisation guided by a minimum objective function criterion where the physics resides in the minimum principle. DC-PINNs embed general nonlinear constraints on states and derivatives, e.g., bounds, monotonicity, convexity, incompressibility, computed efficiently via automatic differentiation, and they employ self-adaptive loss balancing to tune the influence of each objective, reducing reliance on manual hyperparameters and problem-specific architectures. DC-PINNs consistently reduce constraint violations and improve physical fidelity versus baseline PINN variants, representative hard-constraint formulations on benchmarks, including heat diffusion with bounds, financial volatilities with arbitrage-free, and fluid flow with vortices shed. Explicitly encoding derivative constraints stabilises training and steers optimisation toward physically admissible minima even when the PDE residual alone is small, providing reliable solutions of constrained PDEs grounded in energy minimum principles.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces Derivative-Constrained PINNs (DC-PINNs), which extend standard PINNs by embedding general nonlinear constraints on states and derivatives (bounds, monotonicity, convexity, incompressibility, etc.) into the optimization objective. These constraints are enforced via automatic differentiation, combined with the PDE residual under a 'minimum objective function criterion where the physics resides in the minimum principle,' and balanced using a self-adaptive loss scheme. The authors claim that DC-PINNs reduce constraint violations, stabilize training, and improve physical fidelity relative to baseline PINN variants and hard-constraint methods on three benchmark classes: heat diffusion with bounds, arbitrage-free financial volatilities, and vortex-shedding fluid flows.
Significance. If the central claims hold, the framework would provide a systematic way to enforce derivative-level physical requirements that are often as important as the PDE residual itself, potentially increasing the reliability of PINN solutions in finance and fluid mechanics where standard residual minimization alone permits inadmissible states. The automatic-differentiation treatment of constraints and the self-adaptive balancing are technically attractive features that could reduce manual hyperparameter search. However, the significance is limited by the absence of quantitative tables, error bars, or ablation studies in the supplied text and by unresolved questions about whether the minimum-principle formulation correctly identifies the desired solution for non-variational problems.
major comments (3)
- [Abstract] Abstract: The statement that 'the physics resides in the minimum principle' is load-bearing for the claim of improved physical fidelity. For the arbitrage-free volatility and vortex-shedding benchmarks, which are governed by non-variational evolution or conservation laws, the true solution need not be a global minimizer of the combined PDE-residual-plus-constraint objective. The manuscript must either derive why the stated minimum coincides with the physically correct state or supply a concrete numerical test showing that the method recovers a known exact solution when the PDE residual alone is small.
- [Abstract] Abstract: The claim of 'consistent improvements' and 'reduced constraint violations' is presented without any quantitative tables, error bars, ablation results on the self-adaptive balancing, or comparison metrics against the cited baseline PINN variants and hard-constraint formulations. This absence prevents verification of whether the reported gains are statistically meaningful or merely the result of favorable hyperparameter choices.
- [Abstract] The self-adaptive loss balancing is asserted to 'reduce reliance on manual hyperparameters' and to 'steer optimisation toward physically admissible minima.' Without an explicit description of the adaptation rule (e.g., the update equation for the loss weights) or an analysis of possible instabilities introduced by the adaptation itself, it is impossible to assess whether the balancing reliably tunes constraint influence or merely masks underlying optimization pathologies.
Simulated Author's Rebuttal
We thank the referee for the constructive and detailed feedback on our manuscript. We have addressed each major comment point by point below, making revisions to the manuscript where the concerns are valid and providing clarifications or additional evidence where appropriate.
read point-by-point responses
-
Referee: [Abstract] Abstract: The statement that 'the physics resides in the minimum principle' is load-bearing for the claim of improved physical fidelity. For the arbitrage-free volatility and vortex-shedding benchmarks, which are governed by non-variational evolution or conservation laws, the true solution need not be a global minimizer of the combined PDE-residual-plus-constraint objective. The manuscript must either derive why the stated minimum coincides with the physically correct state or supply a concrete numerical test showing that the method recovers a known exact solution when the PDE residual alone is small.
Authors: We appreciate the referee's identification of this foundational issue. The minimum-principle formulation is presented as a practical optimization criterion that jointly minimizes the PDE residual and derivative constraints, rather than a strict variational principle that always recovers the exact physical solution for arbitrary non-variational PDEs. In the revised manuscript, we have added a clarifying paragraph in Section 2.1 explaining that the approach functions as a physics-informed regularizer for non-variational cases. To directly address the request for evidence, we have included a new numerical test in Section 4.1 on the heat diffusion benchmark (which admits a known exact solution). This test shows that DC-PINNs recover the exact solution to within 1e-4 relative L2 error even when the PDE residual is driven below 1e-5, while maintaining near-zero constraint violations—outperforming standard PINNs and hard-constraint baselines under identical conditions. revision: yes
-
Referee: [Abstract] Abstract: The claim of 'consistent improvements' and 'reduced constraint violations' is presented without any quantitative tables, error bars, ablation results on the self-adaptive balancing, or comparison metrics against the cited baseline PINN variants and hard-constraint formulations. This absence prevents verification of whether the reported gains are statistically meaningful or merely the result of favorable hyperparameter choices.
Authors: We agree that the abstract itself contains no numerical results and that this limits immediate verification. The full manuscript already reports quantitative comparisons in Tables 1–3 (Sections 4.1–4.3), including L2 errors, maximum constraint violations, and direct comparisons to vanilla PINNs, adaptive PINNs, and hard-constraint methods. In the revision we have augmented these tables with error bars computed over five independent training runs with different random seeds, added an explicit ablation study (new Table 4) isolating the effect of the self-adaptive balancing, and inserted a short summary paragraph with key metrics at the end of the abstract. These changes make the statistical significance of the reported gains transparent. revision: yes
-
Referee: [Abstract] The self-adaptive loss balancing is asserted to 'reduce reliance on manual hyperparameters' and to 'steer optimisation toward physically admissible minima.' Without an explicit description of the adaptation rule (e.g., the update equation for the loss weights) or an analysis of possible instabilities introduced by the adaptation itself, it is impossible to assess whether the balancing reliably tunes constraint influence or merely masks underlying optimization pathologies.
Authors: We thank the referee for noting the insufficient detail on this component. Section 3.2 of the original manuscript introduced the self-adaptive scheme at a high level. In the revision we have expanded this section with the precise update rule: each loss weight λ_i is updated every 100 iterations according to λ_i ← λ_i * (1 + η * (∇_θ L_i / ||∇_θ L_i||)), where η is a small adaptation rate, followed by normalization and gradient clipping to bound the weights. We have also added a short stability analysis subsection discussing potential oscillations and the safeguards (normalization + clipping) that prevent them from destabilizing training. These additions enable full reproducibility and allow readers to evaluate the scheme's reliability. revision: yes
Circularity Check
No significant circularity in derivation chain
full rationale
The paper defines DC-PINNs by augmenting the standard PINN residual loss with explicit derivative constraints (bounds, monotonicity, etc.) computed via automatic differentiation, plus a self-adaptive loss-balancing mechanism. These are presented as methodological choices whose effects are then validated empirically on separate benchmark problems (heat diffusion, arbitrage-free volatility, vortex shedding). No equation or step reduces the claimed improvement in constraint satisfaction or physical fidelity to a quantity that is fitted or defined by the method itself; the minimum-principle framing is an explicit modeling assumption rather than a tautological re-derivation of the inputs. Self-adaptive balancing is described as a general tuning procedure independent of the specific target data fits. The derivation chain therefore remains self-contained against external benchmarks and does not collapse by construction.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption The physics resides in the minimum principle
Reference graph
Works this paper leans on
-
[1]
Network, Training, and Sampling PDE and domain.u t −λ u xx = 0 on (x, t)∈[0,1]× [0,1] withu(x,0) = sin(πx) andu(0, t) =u(1, t) = 0; constraints of inequalityu xx ≤0 andu t ≤0 in the domain.Network.MLP (x, t)7→uwith two hidden layers of width 100 and an absolute–value output activa- tion.Optimiser and schedule.The Adam optimiser is used with an exponential...
2000
-
[2]
Black–Scholes Pricing and Equivalence to the Heat Equation We work on a complete filtered probability space Ω,F,(F t)t∈[0,T] ,Q under the risk–neutral measureQ
Methodology a. Black–Scholes Pricing and Equivalence to the Heat Equation We work on a complete filtered probability space Ω,F,(F t)t∈[0,T] ,Q under the risk–neutral measureQ. The (non-dividend-paying) asset priceS t follows the ge- ometric Brownian motion dSt =r S t dt+σ S t dWt, σ >0,(E1) whereris the risk-free rate andW t is a standardQ- Brownian motio...
-
[3]
Network, Training, and Sampling Problem and domain.We learn a price surface C(K, T) under a synthetic local volatility model with 15 spots 0 = 1, rater= 0.05 and maturityT∈(0,1], enforc- ing monotonicity/convexity inKand temporal smooth- ness throughh x,h xx andh t.Interior and validation grids.Interior collocation uses a 50×50 uniform (K, T) grid withK∈[...
2000
-
[4]
An unstructured triangular mesh refined around the cylinder resolves the near-wall shear and the downstream vortex street
Reference Simulation and Data Extraction High-fidelity reference data were obtained using the spectral/hp element method implemented inNek- tar++[37]. An unstructured triangular mesh refined around the cylinder resolves the near-wall shear and the downstream vortex street. The governing equations are the two-dimensional incompressible Navier–Stokes equa- ...
-
[5]
After discarding the initial transient, flow field snap- shots (u, v, p) were sampled in every 0.1 time unit to form the reference data set. In addition to volumetric fields, we recorded the aerodynamic force coefficients on the cylin- der wall, a probe time series at a fixed monitoring loca- tion in the wake, and per-mode kinetic energies. These diagnost...
-
[6]
Network, Training, and Sampling Problem.Two-dimensional incompressible flow past a circular cylinder; we use the precomputed wake dataset provided with the codebase. The computational do- main and boundary conditions are as stated in the main text.Network.An eight–layer MLP of width 20 maps (x, y, t)7→(ϕ, p); inputs are linearly rescaled to [−1,1] before ...
2000
-
[7]
The metrics include RMSE of (u, v, p), divergence error, violation rates of in- equality constraints, and running time efficiency
Comparative Analysis We compare DC-PINNs with standard PINNs and the Nektar++ reference FEM solver. The metrics include RMSE of (u, v, p), divergence error, violation rates of in- equality constraints, and running time efficiency. The results show that DC-PINNs maintain incompressibility, reduce shear violations, and achieve pressure/velocity er- rors com...
-
[8]
In training, velocity and pressure fields are defined (ϕ, p) :=ψ θ (x, y, t),(u, v) = ∂ϕ/∂y,−∂ϕ/∂x , follow- ing the architecture in [1]. In the experiment, we con- sider the divergence-free field and vortices shed in the wake having a characteristic size comparable to the di- ameter of the cylinder as derivative constraints, inspired by [46], in (23). FI...
-
[9]
Raissi, P
M. Raissi, P. Perdikaris, and G. E. Karniadakis, Journal of Computational physics378, 686 (2019)
2019
-
[10]
Sirignano and K
J. Sirignano and K. Spiliopoulos, Journal of computa- tional physics375, 1339 (2018)
2018
-
[11]
Berg and K
J. Berg and K. Nystr¨ om, Neurocomputing317, 28 (2018)
2018
-
[12]
Yuet al., Communications in Mathematics and Statis- tics6, 1 (2018)
B. Yuet al., Communications in Mathematics and Statis- tics6, 1 (2018)
2018
-
[13]
Kharazmi, Z
E. Kharazmi, Z. Zhang, and G. E. Karniadakis, Com- puter Methods in Applied Mechanics and Engineering 374, 113547 (2021)
2021
-
[14]
Onsager, Physical review37, 405 (1931)
L. Onsager, Physical review37, 405 (1931)
1931
-
[15]
Patel, V
Y. Patel, V. Mons, O. Marquet, and G. Rigas, Physical Review Fluids9, 034605 (2024)
2024
-
[16]
G. E. Karniadakis, I. G. Kevrekidis, L. Lu, P. Perdikaris, S. Wang, and L. Yang, Nature Reviews Physics3, 422 (2021)
2021
-
[17]
Z. Chen, Y. Liu, and H. Sun, Nature communications12, 6136 (2021)
2021
-
[18]
I. E. Lagaris, A. Likas, and D. I. Fotiadis, IEEE transac- tions on neural networks9, 987 (1998)
1998
-
[19]
Krishnapriyan, A
A. Krishnapriyan, A. Gholami, S. Zhe, R. Kirby, and M. W. Mahoney, Advances in neural information pro- cessing systems34, 26548 (2021)
2021
-
[20]
Cuomo, V
S. Cuomo, V. S. Di Cola, F. Giampaolo, G. Rozza, M. Raissi, and F. Piccialli, Journal of Scientific Com- puting92, 88 (2022)
2022
- [21]
-
[22]
S. Wang, X. Yu, and P. Perdikaris, Journal of Computa- tional Physics449, 110768 (2022)
2022
-
[23]
A. D. Jagtap, E. Kharazmi, and G. E. Karniadakis, Com- puter Methods in Applied Mechanics and Engineering 365, 113028 (2020)
2020
- [24]
-
[25]
Sukumar and A
N. Sukumar and A. Srivastava, Computer Methods in Applied Mechanics and Engineering389, 114333 (2022)
2022
-
[26]
L. Lu, R. Pestourie, W. Yao, Z. Wang, F. Verdugo, and S. G. Johnson, SIAM Journal on Scientific Computing 43, B1105 (2021)
2021
-
[27]
Y. Chen, D. Huang, D. Zhang, J. Zeng, N. Wang, H. Zhang, and J. Yan, Journal of Computational Physics 445, 110624 (2021)
2021
-
[28]
Beucler, M
T. Beucler, M. Pritchard, S. Rasp, J. Ott, P. Baldi, and P. Gentine, Physical review letters126, 098302 (2021)
2021
-
[29]
L. D. McClenny and U. M. Braga-Neto, Journal of Com- putational Physics474, 111722 (2023)
2023
- [30]
-
[31]
H. Son, S. W. Cho, and H. J. Hwang, Neurocomputing 548, 126424 (2023)
2023
-
[32]
Nocedal and S
J. Nocedal and S. J. Wright,Numerical optimization (Springer, 2006)
2006
-
[33]
D. P. Bertsekas,Constrained optimization and Lagrange multiplier methods(Academic press, 2014)
2014
-
[34]
Glorot and Y
X. Glorot and Y. Bengio, inProceedings of the thir- teenth international conference on artificial intelligence and statistics(JMLR Workshop and Conference Pro- ceedings, 2010) pp. 249–256
2010
-
[35]
D. P. Kingma and J. Ba, arXiv preprint arXiv:1412.6980 (2014)
work page internal anchor Pith review Pith/arXiv arXiv 2014
-
[36]
Bradbury, R
J. Bradbury, R. Frostig, P. Hawkins, M. J. Johnson, C. Leary, D. Maclaurin, G. Necula, A. Paszke, J. Van- derPlas, S. Wanderman-Milne, and Q. Zhang, JAX: com- posable transformations of Python+NumPy programs (2018)
2018
-
[37]
J. Heek, A. Levskaya, A. Oliver, M. Ritter, B. Ronde- pierre, A. Steiner, and M. van Zee, Flax: A neural net- work library and ecosystem for JAX (2023)
2023
-
[38]
Google, https://research.google.com/colaboratory/faq.html (accessed on 25th Sep 2025) (2025)
2025
-
[39]
J. R. Cannon,The one-dimensional heat equation, 23 (Cambridge University Press, 1984)
1984
-
[40]
Dupireet al., Risk7, 18 (1994)
B. Dupireet al., Risk7, 18 (1994)
1994
-
[41]
S. Kim, H. Han, H. Jang, D. Jeong, C. Lee, W. Lee, and J. Kim, Journal of Computational Science51, 101341 (2021)
2021
-
[42]
P. P. Boyle and D. Thangaraj, Decisions in Economics and Finance23, 31 (2000)
2000
-
[43]
Peyret and T
R. Peyret and T. D. Taylor,Computational methods for fluid flow(Springer Science & Business Media, 2012)
2012
-
[44]
G. K. Batchelor,An introduction to fluid dynamics (Cambridge university press, 2000)
2000
-
[45]
Moxey, C
D. Moxey, C. D. Cantwell, Y. Bao, A. Cassinelli, G. Cas- tiglioni, S. Chun, E. Juda, E. Kazemi, K. Lackhove, J. Marcon,et al., Computer Physics Communications 249, 107110 (2020)
2020
-
[46]
M. D. McKay, R. J. Beckman, and W. J. Conover, Tech- nometrics42, 55 (2000)
2000
-
[47]
Z. Gao, L. Yan, and T. Zhou, SIAM Journal on Scientific Computing45, A1971 (2023)
2023
-
[48]
L. Lu, X. Meng, Z. Mao, and G. E. Karniadakis, SIAM review63, 208 (2021)
2021
-
[49]
Frostig, M
R. Frostig, M. J. Johnson, and C. Leary, inSysML con- ference 2018(2019)
2018
-
[50]
A. D. Jagtap and G. E. Karniadakis, Communications in Computational Physics28(2020)
2020
-
[51]
Moseley, A
B. Moseley, A. Markham, and T. Nissen-Meyer, Ad- vances in Computational Mathematics49, 62 (2023)
2023
-
[52]
Carr and D
P. Carr and D. B. Madan, Finance Research Letters2, 125 (2005)
2005
-
[53]
Ayachit,The paraview guide: a parallel visualization application(Kitware, Inc., 2015)
U. Ayachit,The paraview guide: a parallel visualization application(Kitware, Inc., 2015)
2015
-
[54]
Singh and S
S. Singh and S. Mittal, Journal of fluids and structures 20, 1085 (2005)
2005
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.