Ando's theorem for nonnegative forms
A necessary and sufficient condition for the existence of the infimum of two nonnegative forms is obtained as a generalization of Ando's theorem on the problem of the infimum (in the positive cone) of two positive operators acting in a Hilbert space (see [\textit{T. Ando}, Math. Appl., Dordr. 478, 1--12 (1999; Zbl 0995.47044)]). The author makes use of the concepts of parallel sum and Lebesque type decomposition of nonnegative forms [\textit{S. Hassi}, \textit{Z. Sebestyen} and \textit{H. S. V. de Snoo}, J. Funct. Anal. 257, No. 12, 3858--3894 (2009; Zbl 1185.47002)].
scientific article; zbMATH DE number 6121304