# Relationship history for MSHA mine 3606535

Current hierarchy: **Simpson Marshall J → Marshall J Simpson → Petro**

- 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:** Kravetsky Charles → Petro; 1975-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Charles Kravetsky → Petro; 1977-10-01 to 1978-11-30; source msha-controller-operator-history
- **controller_controls_operator:** Kravetsky Charles → Charles Kravetsky; 1977-10-01 to 1978-11-30; source msha-controller-operator-history
- **controller_controls_mine:** Simpson Marshall J → Petro; 1978-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Marshall J Simpson → Petro; 1978-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Simpson Marshall J → Marshall J Simpson; 1978-12-01 to current/open; source msha-controller-operator-history