# Relationship history for MSHA mine 0503781

Current hierarchy: **Holland Michael R → Michael R Holland → Bull Durham**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Union Carbide Corp → Bull Durham; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Holland Michael R → Bull Durham; 1979-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Union Carbide Corp → Bull Durham; 1982-06-01 to 1987-03-08; source msha-controller-operator-history
- **controller_controls_operator:** Union Carbide Corp → Union Carbide Corp; 1982-06-01 to 1987-03-08; source msha-controller-operator-history
- **controller_controls_mine:** Mendisco Mark & Marce → Bull Durham; 1987-02-12 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mendisco Mining → Bull Durham; 1987-03-09 to 1990-06-26; source msha-controller-operator-history
- **controller_controls_operator:** Mendisco Mark & Marce → Mendisco Mining; 1987-03-09 to 1990-06-26; source msha-controller-operator-history
- **operator_operates_mine:** Michael R Holland → Bull Durham; 1990-06-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holland Michael R → Michael R Holland; 1990-06-27 to current/open; source msha-controller-operator-history