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Minor Math Jaxing
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Daniele Tampieri
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Is it possible to show for $u:\Omega\subset\mathbb{R}^3\rightarrow \mathbb{R}^3$ that $$\||\nabla(\nabla\cdot u)\||_2^2\leq C\||\Delta u\||_2^2?$$$$\||\nabla(\nabla\cdot u)|\|_2^2\leq C\||\Delta u|\|_2^2?$$

Here $\||f\||_2$$\||f|\|_2$ is the norm in $(L^2(\Omega))^3$ and derivatives are taken in the sense of distributions.

Is it possible to show for $u:\Omega\subset\mathbb{R}^3\rightarrow \mathbb{R}^3$ that $$\||\nabla(\nabla\cdot u)\||_2^2\leq C\||\Delta u\||_2^2?$$

Here $\||f\||_2$ is the norm in $(L^2(\Omega))^3$ and derivatives are taken in the sense of distributions.

Is it possible to show for $u:\Omega\subset\mathbb{R}^3\rightarrow \mathbb{R}^3$ that $$\||\nabla(\nabla\cdot u)|\|_2^2\leq C\||\Delta u|\|_2^2?$$

Here $\||f|\|_2$ is the norm in $(L^2(\Omega))^3$ and derivatives are taken in the sense of distributions.

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Is it possible to bound the L2 norm of the gradient of a divergent by the L2 norm of the Lapacian?

Is it possible to show for $u:\Omega\subset\mathbb{R}^3\rightarrow \mathbb{R}^3$ that $$\||\nabla(\nabla\cdot u)\||_2^2\leq C\||\Delta u\||_2^2?$$

Here $\||f\||_2$ is the norm in $(L^2(\Omega))^3$ and derivatives are taken in the sense of distributions.