Proving two processes equivalent modulo branching bisimulation can be quite difficult and laborious.

The cones and foci method seeks to simplify proving equivalence by assuming that, in most implementations, internal actions progress towards a state in which only externally visible actions are possible.

In this talk, we will discuss the original technique, its incompleteness, and extend upon it such that it can also be used to prove two processes equivalent modulo divergence-preserving branching bisimulation.