# Relationship history for MSHA mine 4105293

Current hierarchy: **John B  Frerich → MOBILE CRUSHING & SCREENING, INC → PORTABLE 8 KOLBERG 4250**

- 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:** John B  Frerich → PORTABLE 8 KOLBERG 4250; 2013-07-31 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** MOBILE CRUSHING & SCREENING, INC → PORTABLE 8 KOLBERG 4250; 2017-08-25 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John B  Frerich → MOBILE CRUSHING & SCREENING, INC; 2017-08-25 to current/open; source msha-controller-operator-history