# Relationship history for MSHA mine 3607104

Current hierarchy: **Bechtel William → A B C Coal Company Inc → Lombardo Strip**

- 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:** Testa Trucking → Lombardo Strip; 1981-03-01 to 1986-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Testa Anne → Lombardo Strip; 1981-03-01 to 1986-01-31; source msha-controller-operator-history
- **controller_controls_operator:** Testa Anne → Testa Trucking; 1981-03-01 to 1986-01-31; source msha-controller-operator-history
- **operator_operates_mine:** A B C Coal Company Inc → Lombardo Strip; 1986-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bechtel William → Lombardo Strip; 1986-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bechtel William → A B C Coal Company Inc; 1986-02-01 to current/open; source msha-controller-operator-history