Let ϕ: [0,1] → [0,1] be a nondecreasing continuous function such that ϕ(x) > x for all x ∈ (0,1). Let the operator be defined on L₂[0,1]. We prove that has a finite number of nonzero eigenvalues if and only if ϕ(0) > 0 and ϕ(1-ε) = 1 for some 0 < ε < 1. Also, we show that the spectral trace of the operator always equals 1.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm185-1-3, author = {Ignat Domanov}, title = {On the spectrum of the operator which is a composition of integration and substitution}, journal = {Studia Mathematica}, volume = {187}, year = {2008}, pages = {49-65}, zbl = {1156.47034}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm185-1-3} }
Ignat Domanov. On the spectrum of the operator which is a composition of integration and substitution. Studia Mathematica, Tome 187 (2008) pp. 49-65. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm185-1-3/