# Relationship history for MSHA mine 2500868

Current hierarchy: **Joseph F  Sempek Jr → Sempek Sand & Gravel → SEMPEK SAND & GRAVEL**

- 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:** Sempek Sand & Gravel → SEMPEK SAND & GRAVEL; 1950-01-01 to 2018-10-22; source msha-controller-operator-history
- **controller_controls_mine:** Joe  Sempek Sr → SEMPEK SAND & GRAVEL; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Joe  Sempek Sr → Sempek Sand & Gravel; 1950-01-01 to 2018-10-22; source msha-controller-operator-history
- **operator_operates_mine:** Sempek Sand & Gravel → SEMPEK SAND & GRAVEL; 2018-10-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Joseph F  Sempek Jr → SEMPEK SAND & GRAVEL; 2018-10-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Joseph F  Sempek Jr → Sempek Sand & Gravel; 2018-10-23 to current/open; source msha-controller-operator-history