# Relationship history for MSHA mine 4503157

Current hierarchy: **Emma  Schmid → George Schmid & Sons Inc → Portable Crusher**

- 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

- **controller_controls_mine:** Emma  Schmid → Portable Crusher; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** George Schmid & Sons Inc → Portable Crusher; 1988-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Emma  Schmid → George Schmid & Sons Inc; 1988-03-01 to current/open; source msha-controller-operator-history