Bifurcations of Steiner Minimal Trees and Minimal Fillings for Non-Convex Four-Point Boundaries and Steiner Subratio for the Euclidean Plane / E. I. Stepanova. // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika. 2016. № 2. P. 48-51 [Moscow Univ. Math. Bulletin. Vol. 72, N 2, 2017. P. 79-81].
Bifurcation diagrams for topologies of Steiner minimal trees and minimal fillings for non-convex four-point boundaries in the Euclidean plane are constructed. Using this result, the four-pointed Steiner subratio of the Euclidean plane is obtained. All configurations which it is attained at are found.
Key words: Steiner minimal tree, minimal filling, Steiner subratio.