# Relationship history for MSHA mine 4603173

Current hierarchy: **Carl R  Johnson → Taco Mining Company → Robbie-B No 1 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Bedford Coal Company → Robbie-B No 1 Mine; 1950-01-01 to 1976-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Seavolt G W Jr → Robbie-B No 1 Mine; 1950-01-01 to 1976-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Seavolt G W Jr → Bedford Coal Company; 1950-01-01 to 1976-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Taco Mining Company → Robbie-B No 1 Mine; 1976-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Carl R  Johnson et al → Robbie-B No 1 Mine; 1976-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carl R  Johnson et al → Taco Mining Company; 1976-06-01 to current/open; source msha-controller-operator-history