# Relationship history for MSHA mine 2902285

Current hierarchy: **Erich F  Barmann → Tecumseh Materials → Techmat/Levy**

- 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:** Erich F  Barmann → Techmat/Levy; 1997-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Tecumseh Materials → Techmat/Levy; 2005-06-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Erich F  Barmann → Tecumseh Materials; 2005-06-02 to current/open; source msha-controller-operator-history