The string graph (Myers 2005) is a simplified graph containing only the irreducible edges of the overlap graph. In the overlap graph and string graph approach, an important step is to find the longest suffix-prefix overlap between all pairs of reads \((S_i, S_j)\). This first requires a thorough review of existing string graph algorithms and assemblers (Koren et al. 2017; Nurk et al. 2020; Cheng et al. 2021; Simpson and Durbin 2011; Rasmussen, Stoye, and Myers 2005), including new developments for diploid assembly that are able to create separate assemblies for the two copies of each chromosome.