Diagram showing an abstract representation of a Pegasys DAG. A): Consider v 1: this could be an input sequence that is used by two sequence analysis programs v 2 and v 3. v 4 is dependent on the output of both v 2 and v 3 and therefore cannot execute until v 2 and v 3 have completed. In this diagram, v 2 and v 3 will be executed in parallel as will v 4 and v 5. B): DAG in the case where v 3 produces two instances of the expected output to v 5. The sub-DAG rooted at v 5 replicates itself (v 5a and v 5b) for each instance of its input. All of the new sub-DAGs are executed in parallel.