# Relationship history for MSHA mine 3503414

Current hierarchy: **D A  Doughty → D A Doughty & Sons → Doughty Portable Crusher #2**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** D A  Doughty → Doughty Portable Crusher #2; 1986-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** D A Doughty & Sons → Doughty Portable Crusher #2; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** D A  Doughty → D A Doughty & Sons; 1994-10-01 to current/open; source msha-controller-operator-history