  We present a self-consistent calculation of the four-gluon vertex of Landau
gauge Yang--Mills theory from a truncated Dyson--Schwinger equation. The
equation contains the leading diagrams in the ultraviolet and is solved using
as the only input results for lower Green functions from previous
Dyson--Schwinger calculations that are in good agreement with lattice data. All
quantities are therefore fixed and no higher Green functions enter within this
truncation. Our self-consistent solution resolves the full momentum dependence
of the vertex but is limited to the tree-level tensor structure at the moment.
Calculations of selected dressing functions for other tensor structures from
this solution are used to exemplify that they are suppressed compared to the
tree-level structure except for possible logarithmic enhancements in the deep
infrared. Our results furthermore allow one to extract a qualitative fit for
the vertex and a running coupling.
