# Relationship history for MSHA mine 3608903

Current hierarchy: **Darryl  Koperna → Short Mt Coal Company → Short Mt Slope**

- 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

- **operator_operates_mine:** Short Mt Coal Company → Short Mt Slope; 2001-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hoffman David → Short Mt Slope; 2001-01-01 to 2002-09-15; source msha-controller-operator-history
- **controller_controls_operator:** Hoffman David → Short Mt Coal Company; 2001-01-01 to 2002-09-15; source msha-controller-operator-history
- **controller_controls_mine:** Darryl  Koperna → Short Mt Slope; 2002-09-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Darryl  Koperna → Short Mt Coal Company; 2002-09-16 to current/open; source msha-controller-operator-history