• A ntaural loop is a strongly connected region
• Each strongly connected region is not a loop

Reducible Flow Graphs

• A graph is reducible if applying a sequence of transformations reduce it to a single node
• A flow graph G=(N,E) is reducible if E can be partitioned into two disjoint groups Eb and Ef such that:
  • (N,Ef ) forms an acyclic graph in which every node can be reached from entry
  • Eb are the backw edges, edges whose heads dominate their tails.

Example of a Non Reducible Flow Graph