# Relationship history for MSHA mine 3607698

Current hierarchy: **Grubbs E M → E M Grubbs → Pit #1 & 2**

- 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

- **operator_operates_mine:** E M Grubbs → Pit #1 & 2; 1985-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Grubbs E M → Pit #1 & 2; 1985-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grubbs E M → E M Grubbs; 1985-05-01 to current/open; source msha-controller-operator-history