# Relationship history for MSHA mine 3200423

Current hierarchy: **Scott  Dvorak; Rick  Lee → Don Dvorak Gravel Inc → Don Dvorak Gravel Inc**

- 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:** Dvorak Pit & Plant → Don Dvorak Gravel Inc; 1950-01-01 to 2014-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Donald  Dvorak → Don Dvorak Gravel Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald  Dvorak → Dvorak Pit & Plant; 1950-01-01 to 2014-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Don Dvorak Gravel Inc → Don Dvorak Gravel Inc; 2014-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rick  Lee et al → Don Dvorak Gravel Inc; 2014-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rick  Lee et al → Don Dvorak Gravel Inc; 2014-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Scott  Dvorak et al → Don Dvorak Gravel Inc; 2014-07-01 to current/open; source msha-controller-operator-history