# Relationship history for MSHA mine 4608710

Current hierarchy: **Billy R  Daugherty → Darty Leasing Inc → Mine 20 West**

- 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:** Billy R  Daugherty → Mine 20 West; 1991-10-28 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Maybelle Coal Inc → Mine 20 West; 1998-03-01 to 2005-02-02; source msha-controller-operator-history
- **controller_controls_mine:** Bruce  Hagerman → Mine 20 West; 1998-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bruce  Hagerman → Maybelle Coal Inc; 1998-03-01 to 2005-02-02; source msha-controller-operator-history
- **operator_operates_mine:** Darty Leasing Inc → Mine 20 West; 2005-02-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Billy R  Daugherty → Darty Leasing Inc; 2005-02-03 to current/open; source msha-controller-operator-history