A Complete Inference System for Regular Processes with Silent Moves

We study the notion of bisimulation between process graphs with silent or invisible steps (τ-steps). This leads to a normalisation or minimalisation result for regular processes with τ-steps and subject to operations + (alternative composition), · (sequential composition) and ∥ (parallel composition or free merge), thereby answering a question of MTLNER [10] and proving the consistency of a version of Koomen's fair abstraction rule.