18.5.2 creates a set, C, of constraint formulas, then attempts to pick one, based on the property that "no input variable depends on the resolution (§18.4) of an output variable of another constraint". (See also the modification to these sentence from JDK-8039299.)

The text then proceeds to talk directly about dependencies between constraints:

"If this subset is empty, then there is a cycle (or cycles) in the graph of dependencies between constraints. In this case, all constraints are considered that participate in a dependency cycle (or cycles) and do not depend on any constraints outside of the cycle (or cycles)."

We should be more explicit about how we define dependencies between constraints (namely, via the interaction between input/output variables, as quoted above).