# Relationship history for MSHA mine 4104589

Current hierarchy: **Billy R  Grimmett → Grimmett Brothers Inc → Grimmett Brothers Portable Crusher #1**

- 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

- **controller_controls_mine:** Billy R  Grimmett  et al → Grimmett Brothers Portable Crusher #1; 1981-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Grimmett Brothers Inc → Grimmett Brothers Portable Crusher #1; 2006-03-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Billy R  Grimmett  et al → Grimmett Brothers Inc; 2006-03-21 to current/open; source msha-controller-operator-history