# Relationship history for MSHA mine 1001957

Current hierarchy: **Troy  Schwartz → Schwartz Construction → PORTABLE PLANT**

- 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:** Schwartz Construction → PORTABLE PLANT; 1999-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Troy  Schwartz → PORTABLE PLANT; 1999-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Troy  Schwartz → Schwartz Construction; 1999-05-01 to current/open; source msha-controller-operator-history