Fig. 2
From: Gramtools enables multiscale variation analysis with genome graphs
Gramtools requires variation to be expressed as a nested directed, acyclic graph (DAG). A nested DAG represents the genome as a DAG with a single source and sink, which can be decomposed into a succession of subgraphs (or sites). Each site starts with an opening node, and finishes with a closing node, and consists of strictly nested sub-sites. This allows hierarchical genotyping of alternate alleles. Strict nesting means that sub-sites must close off and complete before their parent site and without connecting to different sub-sites (e.g. the dotted pink edges would not be permitted)