# Relationship history for MSHA mine 3604597

Current hierarchy: **Rochester & Pittsburgh Coal Company → Helvetia Coal Company → Lucerne No 8 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:** Rochester & Pittsburgh Coal Company → Lucerne No 8 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Williamson Shaft Contracting Company → Lucerne No 8 Mine; 1973-03-01 to 1974-10-28; source msha-controller-operator-history
- **controller_controls_mine:** Williamson Shaft Contracting Company → Lucerne No 8 Mine; 1973-03-01 to 1974-10-28; source msha-controller-operator-history
- **controller_controls_operator:** Williamson Shaft Contracting Company → Williamson Shaft Contracting Company; 1973-03-01 to 1974-10-28; source msha-controller-operator-history
- **operator_operates_mine:** Helvetia Coal Company → Lucerne No 8 Mine; 1974-10-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rochester & Pittsburgh Coal Company → Helvetia Coal Company; 1974-10-29 to current/open; source msha-controller-operator-history