A precedence graph is a directed acyclic graph whose nodes corresponds to individual statements.
An edge from 
to 
, implies that statement can only be executed after statement 
has completed execution.
In the above diagram following precedence relation is shown:
- S2 and S3 can be executed only after S1 has finished execution.
- S4 can be executed only after S2 has completed execution.
- S5 can be executed only after S2, S3, and S4 have finished execution.
The precedence graph is also a dependency graph.
