# Relationship history for MSHA mine 4000642

Current hierarchy: **Tschudy Kenneth → M & K Coal Co Inc → M & K Coal Company**

- 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:** A & B Coal Company → M & K Coal Company; 1950-01-01 to 1973-11-01; source msha-controller-operator-history
- **controller_controls_mine:** A & B Coal Company → M & K Coal Company; 1950-01-01 to 1973-11-01; source msha-controller-operator-history
- **controller_controls_operator:** A & B Coal Company → A & B Coal Company; 1950-01-01 to 1973-11-01; source msha-controller-operator-history
- **operator_operates_mine:** Baird & Long Coal Company → M & K Coal Company; 1973-11-02 to 1975-01-13; source msha-controller-operator-history
- **controller_controls_mine:** Baird Luther & Wn H Long → M & K Coal Company; 1973-11-02 to 1976-10-31; source msha-controller-operator-history
- **controller_controls_operator:** Baird Luther & Wn H Long → Baird & Long Coal Company; 1973-11-02 to 1975-01-13; source msha-controller-operator-history
- **operator_operates_mine:** M & K Coal Co Inc → M & K Coal Company; 1975-01-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tschudy Kenneth Et Al → M & K Coal Company; 1975-01-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tschudy Kenneth Et Al → M & K Coal Co Inc; 1975-01-14 to current/open; source msha-controller-operator-history