Back to Search
Start Over
On Courant’s Nodal Domain Property for Linear Combinations of Eigenfunctions Part II
- Source :
- Springer Proceedings in Mathematics & Statistics ISBN: 9783030684891
- Publication Year :
- 2021
- Publisher :
- Springer International Publishing, 2021.
-
Abstract
- According to Courant's theorem, an eigenfunction as\-sociated with the $n$-th eigenvalue $\lambda_n$ has at most $n$ nodal domains. A footnote in the book of Courant and Hilbert, states that the same assertion is true for any linear combination of eigenfunctions associated with eigenvalues less than or equal to $\lambda_n$. We call this assertion the \emph{Extended Courant Property}.\smallskip In this paper, we propose simple and explicit examples for which the extended Courant property is false: convex domains in $\R^n$ (hypercube and equilateral triangle), domains with cracks in $\mathbb{R}^2$, on the round sphere $\mathbb{S}^2$, and on a flat torus $\mathbb{T}^2$.
- Subjects :
- Discrete mathematics
010102 general mathematics
Regular polygon
Mathematics::Spectral Theory
Eigenfunction
16. Peace & justice
Equilateral triangle
01 natural sciences
010101 applied mathematics
Combinatorics
Simple (abstract algebra)
Domain (ring theory)
Hypercube
0101 mathematics
Linear combination
Mathematics::Symplectic Geometry
Eigenvalues and eigenvectors
Mathematics
Subjects
Details
- ISBN :
- 978-3-030-68489-1
- ISBNs :
- 9783030684891
- Database :
- OpenAIRE
- Journal :
- Springer Proceedings in Mathematics & Statistics ISBN: 9783030684891
- Accession number :
- edsair.doi...........0d993cd98809a121c78afc6aef6d2ba8