# Relationship history for MSHA mine 4406587

Current hierarchy: **Hay Walker W → D O & W Coal Company Inc → No 12**

- 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:** Hay Walker W Et Al → No 12; 1983-08-04 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ivy Branch Coal Company Inc → No 12; 1990-05-01 to 1993-07-18; source msha-controller-operator-history
- **controller_controls_mine:** Gary  Baker → No 12; 1990-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gary  Baker → Ivy Branch Coal Company Inc; 1990-05-01 to 1993-07-18; source msha-controller-operator-history
- **operator_operates_mine:** D O & W Coal Company Inc → No 12; 1993-07-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hay Walker W Et Al → D O & W Coal Company Inc; 1993-07-19 to current/open; source msha-controller-operator-history