Figure 1 : Illustration of the notion of layers: Given M = (a1, a2, a3) (thick tentacular hyperarcs), and a solution A′ containing M, G(A′) (dashed arcs) consists of a forest covering all T′, i.e. each vertex in tT′ is part of a tree whose source is in a lower “layer” than t.

From: A Combinatorial Algorithm for Microbial Consortia Synthetic Design

Figure 1