# Relationship history for MSHA mine 4606390

Current hierarchy: **Horn Steve → Tug Huff Coal Corp → Sewell No 1**

- 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:** Voest-Alpine International Corp → Sewell No 1; 1978-03-22 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Virginia Crews Coal Company → Sewell No 1; 1981-09-01 to 1987-04-16; source msha-controller-operator-history
- **controller_controls_operator:** Voest-Alpine International Corp → Virginia Crews Coal Company; 1981-09-01 to 1987-04-16; source msha-controller-operator-history
- **operator_operates_mine:** Tug Huff Coal Corp → Sewell No 1; 1987-04-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Horn Steve → Sewell No 1; 1987-04-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Horn Steve → Tug Huff Coal Corp; 1987-04-17 to current/open; source msha-controller-operator-history