  Diagrammatic reducibility DR and its generalization vertex asphericity VA are
combinatorial tools developed for detecting asphericity of a 2-complex. Here we
present tests for a relative version of VA that apply to pairs of 2-complexes
$(L,K)$, where $K$ is a subcomplex of $L$. We show that a relative weight test
holds for injective labeled oriented trees, implying that they are VA and hence
aspherical. This strengthens a result obtained by the authors in 2017 and
simplifies the original proof.
