# Relationship history for MSHA mine 4105586

Current hierarchy: **Kiewit Peter Sons' Inc → Kiewit Mining Group → Grindstone**

- 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:** Kiewit Peter Sons' Inc → Grindstone; 2004-08-21 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Kiewit Mining Group → Grindstone; 2021-10-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kiewit Peter Sons' Inc → Kiewit Mining Group; 2021-10-07 to current/open; source msha-controller-operator-history