Complex sentence: Erdős-Diophantine graphs form a subset of the set of Diophantine figures: complete graphs in the Diophantine plane for which the length of all edges are integer numbers.
Split into simpler sentences: Erdős-Diophantine graphs form a subset of the set of Diophantine figures. The latter are defined as complete graphs in the Diophantine plane for which the length of all edges are integer numbers.