Let:

- $X$ be the set of elements
- $R$ be the set of relations
- $R_{2}$ be the set of relations which can be reached from two hops of relations in $R$
- For example,
`(a,c)`

is reached by going through`(a,b) -> (b,c)`

- For example,
- $R_{∗}$ is the entire transitive closure over $R$