In Chapter 1 of his book: "Modules and Rings", John Dauns (on page 7) considers a subset T of an R-module M and defines the R-submodule generated by...
The closed and bounded sets where the functions are non-zero don't have to be of the form $$, do they?
But are we sure that the sets are in the form...
I am confused now. Since the initial data of the initial value problem for the wave equation have compact support, we have that there is some bounded...