Weak Poisson solutions and Lax–Milgram
Research context
postgraduate concept · established · As of 2026-10-10
On a bounded domain, the homogeneous Dirichlet Poisson problem seeks u in H0^1 with integral grad-u·grad-v=<f,v> for every v in H0^1, where f is in H−1.
Key knowledge
On a bounded domain, the homogeneous Dirichlet Poisson problem seeks u in H0^1 with integral grad-u·grad-v=<f,v> for every v in H0^1, where f is in H−1. Poincaré gives coercivity, so Lax–Milgram provides a unique weak solution and ||u||-H0^1 ≤ C||f||-H−1. More generally, a bounded coercive bilinear form on a real Hilbert space has a unique solution for each continuous linear functional.
Values and equations
a(u,v)=ell(v); |a(u,v)|≤C||u||||v||; a(v,v)≥alpha||v||², alpha>0
- a
- Bounded coercive bilinear form on a real Hilbert space
- ell
- Continuous linear functional
- alpha
- Positive coercivity constant
Conditions and scope
- The weak boundary condition is membership in H0^1; coercivity and boundedness are checked in its norm.
- Weak existence does not imply classical second derivatives or smooth boundary regularity.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Author checked this English statement, displayed equation where present and stated hypotheses against these source locations: Chapter 4: weak Dirichlet Laplacian, Poincaré, Theorem 4.20 Lax–Milgram; chapter 6 parabolic energy/Galerkin; chapter 3 compactness; §5.6 Theorems 5.53/5.55 subcritical nonlinear Schrodinger existence. The check is bounded to the recorded claims; no complete proof reconstruction, software proof replay or universal literature completeness is claimed.
2026-10-10 · Author source-body/statement/equation/domain check, with graph associations scoped individually. Separate independent content/source/inventory review is required before branch closure.
Entry details
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