Are we including the program itself as graph-like data? A well-structured program is usually a directed graph. Blocks are the vertices, control flow the edges.
my first set theory class in college ruined me. All I saw were sets. The class was taught using graphs too so it was very visualizable
then I took group theory and became a hippy that believes every problem has multiple perspectives you can see it through that have their own strengths and weaknesses and there's no one true perspective