Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
| <mark>Journal publication date</mark> | 31/07/2021 |
|---|---|
| <mark>Journal</mark> | Journal of Spectral Theory |
| Issue number | 3 |
| Volume | 11 |
| Number of pages | 23 |
| Pages (from-to) | 1255-1277 |
| Publication Status | Published |
| <mark>Original language</mark> | English |
We consider canonical systems and investigate the Szego class, which is defined via the finiteness of the associated entropy functional. Noting that the canonical system may be studied in a variety of gauges, we choose to work in the Arov gauge, in which we prove that the entropy integral is equal to an integral involving the coefficients of the canonical system. This sum rule provides a spectral theory gem in the sense proposed by Barry Simon.