Specifications modelling multiple processes concurrently incrementing a shared variable

This set of specifications is useful for demonstrating many of the interesting properties of TLA+, TLC and model checking.

• Single process increment_1.tla
  • Introduce TLA+ syntax and actions
  • Basic invariants and properties
  • Liveness properties, stuttering and fairness
• Two processes increment_2.tla and the corrected increment_2_lock.tla
  • How to model non-determinism in the Next formula
  • Counter-examples for properties and how we can fix it in this case
• Arbitrary processes increment_g.tla and increment_g_lock.tla
  • Complete (ish) TLA+ syntax
  • State space explosion (increase the number of processes in increment_g.cfg and increment_g_lock.cfg)
  • Symmetry reduction solving the state space explosion

To run: tlc2 increment_{variant}.tla.