# Relationship history for MSHA mine 2601442

Current hierarchy: **Robison Bryant W → Robison Equipment & Construction Company → Hyer Pit**

- 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

- **operator_operates_mine:** Robison Equipment & Construction Company → Hyer Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robison Bryant W → Hyer Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robison Bryant W → Robison Equipment & Construction Company; 1950-01-01 to current/open; source msha-controller-operator-history