# Relationship history for MSHA mine 4503031

Current hierarchy: **Adam  Hill; Alex J  Hill → Fred Hill Materials Inc → PORT TOWNSEND PIT**

- 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:** Alex J  Hill et al → PORT TOWNSEND PIT; 1977-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Fred Hill Materials Inc → PORT TOWNSEND PIT; 1985-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alex J  Hill et al → Fred Hill Materials Inc; 1985-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Adam  Hill et al → Fred Hill Materials Inc; 1985-02-01 to current/open; source msha-controller-operator-history