# Relationship history for MSHA mine 2003511

Current hierarchy: **Glenn  Eisenhardt; Eric  Eisenhardt → Michigan Sand & Gravel → Walker-Indep Contr B1770**

- 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

- **controller_controls_mine:** Glenn  Eisenhardt et al → Walker-Indep Contr B1770; 2014-01-21 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Michigan Sand & Gravel → Walker-Indep Contr B1770; 2015-05-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Glenn  Eisenhardt et al → Michigan Sand & Gravel; 2015-05-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Eric  Eisenhardt et al → Michigan Sand & Gravel; 2015-05-28 to current/open; source msha-controller-operator-history