A similar case of structures that cannot be dissected are specific fused aromatic systems, i.e. aromatic rings that share the same atom with at least two other rings. When removing an aromatic ring sharing a bond with another ring, Scaffold Generator turns the shared bond into a double-bond to preserve the correct hybridisation of the formerly shared atoms in the remaining ring. In arrangements where the aromatic ring to remove shares an atom with at least two other rings, this double-bond insertion is not possible without violating valence rules. Such structures are not dissected as a consequence. This behaviour follows the ring removal algorithm described in the original scaffold tree publication (compare Schuffenhauer et al. Scheme 3). But Scaffold Generator makes one addition here: In the original scaffold tree, this double-bond insertion is only done if an aromatic ring is fused to a non-aromatic ring and the aromatic ring is removed. In Scaffold Generator, it is also done if the remaining ring is aromatic as well. This addition has been made to preserve hybridisations and aromaticity in the remaining ring and to ensure that aromatic ring systems, if they can be dissected, are decomposed into parent scaffolds that can always be represented as valid contributing structures (as opposed to resonance hybrids). As a consequence, Scaffold Generator does not dissect most fused aromatic ring systems, e.g. pyrene. In these systems, most rings cannot be removed without altering hybridisations and bond orders in the remaining ones. And since a partial dissection does not appear reasonable because it would not produce meaningful parent scaffolds, these structures are not dissected at all. A possible future extension to Scaffold Generator could be a routine that extracts meaningful parent scaffolds from fused aromatic systems, e.g. a benzene ring as root scaffold from pyrene and similar structures.