# Relationship history for MSHA mine 4502828

Current hierarchy: **Grady John & W Trotter → Grady & Trotter → Grady Quarry**

- 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:** Grady & Trotter → Grady Quarry; 1980-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Grady John & W Trotter → Grady Quarry; 1980-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grady John & W Trotter → Grady & Trotter; 1980-06-01 to current/open; source msha-controller-operator-history