# Package org.eclipse.viatra.query.runtime.matchers.planning.operations

- Class Summary
  Class | Description
  --- | ---
  PApply | Represents a constraint application on a single parent SubPlan.
  PEnumerate | Represents a base relation defined by the instance set of an enumerable PConstraint; there are no parent SubPlans.
  PJoin | Represents a natural join of two parent SubPlans.
  POperation | Abstract superclass for representing a high-level query evaluation operation.
  PProject | Represents a projection of a single parent SubPlan onto a limited set of variables.
  PStart | No constraints, and no parent SubPlan, just a (possibly empty) set of a priori known (input) variables.