# Relationship history for MSHA mine 4604773

Current hierarchy: **Mason Martin E → Horizon Mining Company → Robin No 2 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

- **controller_controls_mine:** Kinder Herbert E Jr → Robin No 2 Mine; 1974-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Alma Coal Corp → Robin No 2 Mine; 1975-08-20 to 1979-05-29; source msha-controller-operator-history
- **controller_controls_operator:** Kinder Herbert E Jr → Alma Coal Corp; 1975-08-20 to 1979-05-29; source msha-controller-operator-history
- **operator_operates_mine:** Horizon Mining Company → Robin No 2 Mine; 1979-05-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mason Martin E → Robin No 2 Mine; 1979-05-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mason Martin E → Horizon Mining Company; 1979-05-30 to current/open; source msha-controller-operator-history