Illustration of an unsafe unitig. Panel A shows two parts of a sequenced genome X. Regions surrounded by green dashed boxes are the sequenced segments S. The solid blue boxes represent two copies of a repeat. Panel B shows the resulting $G_{\mathrm{basic}}\left(\mathrm{s}{\mathrm{p}}^k\left(\mathcal{S}\right)\right)$, with dashed vertices and edges representing vertices that are in G_basic(sp^k(X)) but not sequenced.