# Relationship history for MSHA mine 4405741

Current hierarchy: **Robray Corp → Big Mountain Coal Corp → #1 Strip**

- 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:** Big Mountain Coal Corp → #1 Strip; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robray Corp → #1 Strip; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robray Corp → Big Mountain Coal Corp; 1981-09-01 to current/open; source msha-controller-operator-history