# Relationship history for MSHA mine 1511673

Current hierarchy: **David F  May → M & W Coal Company Inc → No 1-A 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** David F  May → No 1-A Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M & W Coal Company Inc → No 1-A Mine; 1978-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David F  May → M & W Coal Company Inc; 1978-11-01 to current/open; source msha-controller-operator-history