# Relationship history for MSHA mine 1511731

Current hierarchy: **Morris Joe H & Billy V Hall → M & M Coal Company → No 4 Surface**

- 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:** Morris Joe H & Billy V Hall → No 4 Surface; 1975-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M & M Coal Company → No 4 Surface; 1978-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Morris Joe H & Billy V Hall → M & M Coal Company; 1978-12-01 to current/open; source msha-controller-operator-history