# Relationship history for MSHA mine 2000013

Current hierarchy: **Thomas L  Brayak → Bichler Gravel & Concrete Company → Bichler Quarry**

- 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:** Bichler Gravel & Concrete Company → Bichler Quarry; 1950-01-01 to 1984-07-22; source msha-controller-operator-history
- **controller_controls_mine:** Proksch C A → Bichler Quarry; 1950-01-01 to 1984-07-22; source msha-controller-operator-history
- **controller_controls_operator:** Proksch C A → Bichler Gravel & Concrete Company; 1950-01-01 to 1984-07-22; source msha-controller-operator-history
- **controller_controls_mine:** Thomas L  Brayak → Bichler Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Bichler Gravel & Concrete Company → Bichler Quarry; 1984-07-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomas L  Brayak → Bichler Gravel & Concrete Company; 1984-07-23 to current/open; source msha-controller-operator-history