On the null-spaces of elliptic partial differential operators in 𝑅ⁿ
Homer F. Walker · Transactions of the American Mathematical Society · 1972
The objective of this paper is to generalize the results of Lax and Phillips [4] and Walker [6] to include elliptic partial differential operators of all orders whose coefficients approach constant values at infinity with a certain swiftness. An example is given of an elliptic operator having an infinite-dimensional null-space whose coefficients slowly approach constant limiting values.