# Relationship history for MSHA mine 0504290

Current hierarchy: **Kent John G → Tricon Kent Company → Tricon Kent Co Portable Crushing Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Tricon Kent Company → Tricon Kent Co Portable Crushing Plant; 1987-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kent John G → Tricon Kent Co Portable Crushing Plant; 1987-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kent John G → Tricon Kent Company; 1987-12-01 to current/open; source msha-controller-operator-history