@article {10.3844/jmssp.2007.207.210,
article_type = {journal},
title = {On a Class of Nonhomogeneous Fields in Hilbert Space},
author = {Hatamleh, Raéd},
volume = {3},
year = {2007},
month = {Dec},
pages = {207-210},
doi = {10.3844/jmssp.2007.207.210},
url = {https://thescipub.com/abstract/jmssp.2007.207.210},
abstract = {Two-parametric semigroups of operators in Hilbert space with bounded infinitesimal doubly commuting operators are studied. The characteristics describing deviation of a semigroup from unitary one, when infinitesimal operators are unitary, in particular, nonunitary index, have been introduced. Necessary and sufficient conditions for nonunitary index finiteness have been obtained.},
journal = {Journal of Mathematics and Statistics},
publisher = {Science Publications}
}