{
  "name": "Classical HP-not-HHP regression target",
  "source": "S. B. Fröschle and T. T. Hildebrandt, On Plain and Hereditary History-Preserving Bisimulation, BRICS RS-99-4, 1999.",
  "expected": {
    "HP": true,
    "HHP": false
  },
  "mechanism": [
    "parallel a/b actions can be forward-matched using an order-dependent mapping",
    "a c-continuation forces one particular a-event matching",
    "after backtracking the paired a-events, the remaining b-events would have to stay related",
    "one side can then perform d while the other cannot",
    "therefore hereditary/backtracking closure fails"
  ],
  "status": "literature-grounded regression specification; translation into the ON-RDSS decorated-history checker is the next implementation step"
}