# Relationship history for MSHA mine 4404633

Current hierarchy: **Roberts Thomas W → Calvin Energy Corp → 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** De Voe Robert F Et Al → No 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sunshine Collieries Inc → No 1 Mine; 1977-01-01 to 1979-08-01; source msha-controller-operator-history
- **controller_controls_operator:** De Voe Robert F Et Al → Sunshine Collieries Inc; 1977-01-01 to 1979-08-01; source msha-controller-operator-history
- **operator_operates_mine:** Calvin Energy Corp → No 1 Mine; 1979-08-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Roberts Thomas W Et Al → No 1 Mine; 1979-08-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roberts Thomas W Et Al → Calvin Energy Corp; 1979-08-02 to current/open; source msha-controller-operator-history