# Relationship history for MSHA mine 4105029

Current hierarchy: **John B  Frerich → Mobile Crushing & Screening Inc → Portable 1  P500**

- 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:** John B  Frerich → Portable 1  P500; 2013-07-31 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mobile Crushing & Screening Inc → Portable 1  P500; 2013-08-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John B  Frerich → Mobile Crushing & Screening Inc; 2013-08-08 to current/open; source msha-controller-operator-history