Talk:Capacity of a set

Poorly written section
Under Generalizations, the section Divergence form elliptic operators begins as follows:

"''Solutions to a uniformly elliptic partial differential equation with divergence form
 * $$ \nabla \cdot ( A \nabla u ) = 0 $$

are minimizers of the associated energy functional
 * $$I[u] = \int_D (\nabla u)^T A (\nabla u)\,\mathrm{d}x$$

subject to appropriate boundary conditions.''"

but nowhere in this section (or elsewhere in the article) is the meaning of the symbol "$$A$$" described.

In addition, nothing is stated to connect this "generalization" with the "condenser capacity" or the "Newtonian/harmonic capacity" described in the rest of the article.

I hope someone knowledgeable about this subject can address these serious shortcomings.50.234.60.130 (talk) 23:35, 11 December 2020 (UTC)


 * The article on elliptic partial differential equation tells you what A is. Well, actually, only elliptic operator tells you that. So, yes, this subsection is a bit opaque. The "generalization" is that of moving from the Laplacian $$\nabla^2$$ to a general elliptic operator. 67.198.37.16 (talk) 23:13, 3 February 2024 (UTC)

Fatuous reference
I wish this page told us what capacities are.

It might be reasonable to omit

Solomentsev, E. D. (2001) [1994], "Capacity of a set", Encyclopedia of Mathematics, EMS Press

from the References section. The article title links to https://www.encyclopediaofmath.org/index.php?title=Capacity_of_a_set, whose current content is "There is currently no text in this page. You can search for this page title in other pages, or search the related logs, but you do not have permission to create this page." Scwarebang (talk) 10:37, 16 April 2022 (UTC)


 * EOM URL's were broken by EOM in the last few years. I fixed it just now. Try this one: https://encyclopediaofmath.org/wiki/Capacity 67.198.37.16 (talk) 23:01, 3 February 2024 (UTC)