# Relationship history for MSHA mine 3800730

Current hierarchy: **Thomas Concrete Group AB → Thomas Cement → Simpson Mine**

- 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:** Thomas Cement → Simpson Mine; 2010-09-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Thomas Concrete Group AB → Simpson Mine; 2010-09-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomas Concrete Group AB → Thomas Cement; 2010-09-09 to current/open; source msha-controller-operator-history