# Relationship history for MSHA mine 1800235

Current hierarchy: **Polce Mary L → Mountain Top Coal Company → Buffalo No 2**

- 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:** Franklin Polce Coal Company → Buffalo No 2; 1950-01-01 to 1982-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Polce Franklin → Buffalo No 2; 1950-01-01 to 1982-07-31; source msha-controller-operator-history
- **controller_controls_operator:** Polce Franklin → Franklin Polce Coal Company; 1950-01-01 to 1982-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Mountain Top Coal Company → Buffalo No 2; 1982-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Polce Mary L → Buffalo No 2; 1982-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Polce Mary L → Mountain Top Coal Company; 1982-08-01 to current/open; source msha-controller-operator-history