# Relationship history for MSHA mine 0201135

Current hierarchy: **Stewart John W → Cornerstone Materials Inc → Portable Unit No 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

- **operator_operates_mine:** Hunter Contracting Company → Portable Unit No 1; 1950-01-01 to 1979-11-15; source msha-controller-operator-history
- **controller_controls_mine:** Taddei Armando → Portable Unit No 1; 1950-01-01 to 1979-11-15; source msha-controller-operator-history
- **controller_controls_operator:** Taddei Armando → Hunter Contracting Company; 1950-01-01 to 1979-11-15; source msha-controller-operator-history
- **operator_operates_mine:** Cornerstone Materials Inc → Portable Unit No 1; 1979-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stewart John W → Portable Unit No 1; 1979-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stewart John W → Cornerstone Materials Inc; 1979-11-16 to current/open; source msha-controller-operator-history