# Relationship history for MSHA mine 0502661

Current hierarchy: **Kn Energy Inc → Wyoming Fuel Company → Canadian Strip**

- 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

- **operator_operates_mine:** Sigma Mining Corp → Canadian Strip; 1975-01-01 to 1981-12-14; source msha-controller-operator-history
- **controller_controls_mine:** Wyoming Fuel Co & Centennial Coal Inc → Canadian Strip; 1975-01-01 to 1981-12-14; source msha-controller-operator-history
- **controller_controls_operator:** Wyoming Fuel Co & Centennial Coal Inc → Sigma Mining Corp; 1975-01-01 to 1981-12-14; source msha-controller-operator-history
- **controller_controls_mine:** Kn Energy Inc → Canadian Strip; 1980-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Wyoming Fuel Company → Canadian Strip; 1981-12-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kn Energy Inc → Wyoming Fuel Company; 1981-12-15 to current/open; source msha-controller-operator-history