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Questions about linear partial differential equations. Often used in combination with the top-level tag ap.analysis-of-pdes.

4 votes
0 answers
74 views

The sum of linear partial differential operators of equal strength

If $P$ and $P'$ are linear partial differential operators with constant complex coefficients on $U = \mathring U \subseteq \Bbb R^m$, we say that $P \sim P'$ if and only if $\dfrac {\tilde P} {\tilde …
Alex M.'s user avatar
  • 5,407
4 votes
2 answers
450 views

Hörmander's hypoellipticity theorem for complex coefficients

Hörmander's theorem says that if $L = \sum _{i=1} ^r X_i ^2+ X_0 + f$ on some open subset $U \subseteq \Bbb R$ has the property that the Lie algebra generated by $\{X_0, \dots, X_r\}$ at every point h …
Alex M.'s user avatar
  • 5,407
1 vote
0 answers
95 views

Construct a PDE solution from a net of approximations

Consider $P$ a linear partial differential operator in $\Bbb R ^n$. Consider some boundary condition given in the generic form $C(u) = 0$, that guarantees a unique solution (if any) of $Pu = 0$. Let …
Alex M.'s user avatar
  • 5,407
0 votes
1 answer
395 views

The hypoellipticity of a heat-like operator

I am aware that the heat operator (on a smooth manifold) is hypoelliptic. I am also aware that there are manifolds on which the Schrödinger's operator (with a $\Bbb i = \sqrt {-1}$ multiplying $\frac …
Alex M.'s user avatar
  • 5,407
4 votes
2 answers
367 views

Recognizing Schwartz regular distributions

Are there characterizations of Schwartz regular distributions other than being locally integrable (which does not lend itself to easy manipulations)? To be more detailed: if I want to show that some …
Alex M.'s user avatar
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