Within the study of parametric geometry of numbers, Schmidt and Summerer introduced so-called regular graphs. Roughly speaking, the successive minima functions for the classical simultaneous Diophantine approximation problem have a very special pattern if the vector  induces a regular graph. The regular graph is, in particular, of interest due to a conjecture by Schmidt and Summerer concerning classic approximation constants. This paper aims to provide several new results on the behavior of the successive minima functions for the regular graph. Moreover, we improve the best known upper bounds for the classic approximation constants  provided that the Schmidt-Summerer conjecture is true.

successive minima, lattices, regular graph, uniform Diophantine approximation.