What is "graphlets"

n. (plural of graphlet English)

Graphlets are small connected non-isomorphic induced subgraphs of a large network. Graphlets differ from network motifs, since they must be induced subgraphs, whereas motifs are partial subgraphs. An induced subgraph must contain all edges between its nodes that are present in the large network, while a partial subgraph may contain only some of these edges. Moreover, graphlets do not need to be over-represented in the data when compared with randomized networks, while motifs do.

Graphlets were first introduced by Nataša Pržulj, when they were used as a basis for designing two new highly sensitive measures of network local structural similarities: the relative graphlet frequency distance (RGF-distance) and the graphlet degree distribution agreement (GDD-agreement). Additionally, Pržulj group developed a novel measure of network topological similarity that generalizes the degree of a node in the network to its graphlet degree vector (GDV) or graphlet degree signature.