# Relationship history for MSHA mine 0405515

Current hierarchy: **Rick  Joy → Joy Engineering → Sparrock Pit**

- 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:** Rick  Joy → Sparrock Pit; 2001-10-26 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Joy Engineering → Sparrock Pit; 2002-02-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rick  Joy → Joy Engineering; 2002-02-27 to current/open; source msha-controller-operator-history