Coxeter transformations: construction of deltoids. (English)
Math. Notes 79, No. 5, 643-648 (2006); translation from Mat. Zametki 79, No. 5, 694-699 (2006).
Summary: The Coxeter transformations associated with deltoids (i.e., with graphs in which all simple cycles have length 3) are considered. The structure of the set of all connected deltoids whose spectra do not contain $-1$ is described.