# Relationship history for MSHA mine 1502555

Current hierarchy: **Day & Walker Coal Company → Day & Walker Coal Co → 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** High Top Coal Company Inc → No 2 Mine; 1950-01-01 to 1972-06-01; source msha-controller-operator-history
- **controller_controls_mine:** Rich John W (Ky-Tn-In) → No 2 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rich John W (Ky-Tn-In) → High Top Coal Company Inc; 1950-01-01 to 1972-06-01; source msha-controller-operator-history
- **operator_operates_mine:** Day & Walker Coal Co → No 2 Mine; 1972-06-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Day & Walker Coal Company → No 2 Mine; 1972-06-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Day & Walker Coal Company → Day & Walker Coal Co; 1972-06-02 to current/open; source msha-controller-operator-history