# Relationship history for MSHA mine 4800168

Current hierarchy: **Ashland Inc → Energy Development Company → Vanguard I Mine**

- 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:** Energy Development Company → Vanguard I Mine; 1971-05-01 to 1983-11-27; source msha-controller-operator-history
- **controller_controls_mine:** Iowa Public Service → Vanguard I Mine; 1971-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Iowa Public Service → Energy Development Company; 1971-05-01 to 1983-11-27; source msha-controller-operator-history
- **operator_operates_mine:** Energy Development Company → Vanguard I Mine; 1983-11-28 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc et al → Vanguard I Mine; 1983-11-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc et al → Energy Development Company; 1983-11-28 to current/open; source msha-controller-operator-history