# Relationship history for MSHA mine 2500612

Current hierarchy: **Hoffmeister Robert → Hoffmeister Gravel Company → PIT AND PLANT 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:** Hoffmeister Gravel Company → PIT AND PLANT NO. 1; 1950-01-01 to 1996-04-24; source msha-controller-operator-history
- **controller_controls_mine:** Hoffmeister Frank → PIT AND PLANT NO. 1; 1950-01-01 to 1996-04-24; source msha-controller-operator-history
- **controller_controls_operator:** Hoffmeister Frank → Hoffmeister Gravel Company; 1950-01-01 to 1996-04-24; source msha-controller-operator-history
- **operator_operates_mine:** Hoffmeister Gravel Company → PIT AND PLANT NO. 1; 1996-04-25 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hoffmeister Robert → PIT AND PLANT NO. 1; 1996-04-25 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hoffmeister Robert → Hoffmeister Gravel Company; 1996-04-25 to current/open; source msha-controller-operator-history