# Relationship history for MSHA mine 1509993

Current hierarchy: **Dennison J B → Darby B Corp → No 8 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:** Dennison J B → No 8 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Smith Arthur → No 8 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Smith Coal Company → No 8 Mine; 1976-09-16 to 1977-02-01; source msha-controller-operator-history
- **controller_controls_operator:** Smith Arthur → Smith Coal Company; 1976-09-16 to 1977-02-01; source msha-controller-operator-history
- **operator_operates_mine:** Darby B Corp → No 8 Mine; 1977-02-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dennison J B → Darby B Corp; 1977-02-02 to current/open; source msha-controller-operator-history