Formalization of the Galerkin Construction for the Two-Dimensional Navier--Stokes Equations in Lean
Abstract
We formalize in Lean 4 the Galerkin construction of global Leray--Hopf weak solutions for the unforced two-dimensional Navier--Stokes equations on arbitrary bounded open domains with no-slip boundary conditions. For every initial datum in the solenoidal L2 velocity space, the solution has a weakly continuous velocity path, satisfies the weak equation locally in time, and obeys the energy inequality at every time. For rectangles, we also formalize finite-horizon solutions with continuous forcing in the dual energy space. The development includes divergence-free graph spaces, compact spectral coordinates, transport cancellation, Ladyzhenskaya estimates, and simultaneous space--time compactness. The abstract Hilbert-space results apply to evolution equations with a compact energy-to-velocity embedding and a skew trilinear nonlinearity.
Related
- Global Regularity for the 3D Incompressible Navier–Stokes Equations via the Frohmanian Symplectic Tether: Lean 4 Formalization and Conditional Cubic Comparison Framework (v2.1)
- The Generative Mechanism of Dimension: An Axiomatic Construction of Dimensional Conventions (Constructive Mathematics Series, Paper 6; Lean formalization, model-pair independence, numerical evidence)
- The sharp CFL condition of the piecewise constant sparse grid discontinuous Galerkin method for high-dimensional transport equations
- A Viscous Cascade Construction of Nonunique Leray--Hopf Solutions to the Unforced 3D Navier--Stokes Equations
- Ergodicity for the Two-Dimensional Stochastic Navier-Stokes Equations with Shear-Thickening Viscosity
BibTeX
@misc{wang2026formalization,
title = {{Formalization of the Galerkin Construction for the Two-Dimensional Navier--Stokes Equations in Lean}},
author = {Weinan Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.33033},
eprint = {2609.33033},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.33033},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Formalization of the Galerkin Construction for the Two-Dimensional Navier--Stokes Equations in Lean
AU - Weinan Wang
PY - 2026
DA - 2026/09/27
PB - arXiv
DO - 10.48550/arxiv.2609.33033
UR - https://arxiv.org/abs/2609.33033
AB - We formalize in Lean 4 the Galerkin construction of global Leray--Hopf weak solutions for the unforced two-dimensional Navier--Stokes equations on arbitrary bounded open domains with no-slip boundary conditions. For every initial datum in the solenoidal L^2 velocity space, the solution has a weakly continuous velocity path, satisfies the weak equation locally in time, and obeys the energy inequality at every time. For rectangles, we also formalize finite-horizon solutions with continuous forcing in the dual energy space. The development includes divergence-free graph spaces, compact spectral coordinates, transport cancellation, Ladyzhenskaya estimates, and simultaneous space--time compactness. The abstract Hilbert-space results apply to evolution equations with a compact energy-to-velocity embedding and a skew trilinear nonlinearity.
ER -