# Relationship history for MSHA mine 1517777

Current hierarchy: **David  Grubb → G & P Contractors Inc → Engle Hollow #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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** David  Grubb → Engle Hollow #1; 1989-05-10 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** G & P Contractors Inc → Engle Hollow #1; 1996-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David  Grubb → G & P Contractors Inc; 1996-04-01 to current/open; source msha-controller-operator-history