# Relationship history for MSHA mine 2401986

Current hierarchy: **William J  Hollow → Hollow Contracting Inc → Portable Crusher**

- 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:** Hollow Contracting Inc → Portable Crusher; 1992-09-01 to 1995-04-10; source msha-controller-operator-history
- **controller_controls_mine:** William J  Hollow → Portable Crusher; 1992-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William J  Hollow → Hollow Contracting Inc; 1992-09-01 to 1995-04-10; source msha-controller-operator-history
- **operator_operates_mine:** Montana Materials Llc → Portable Crusher; 1995-04-11 to 1998-05-14; source msha-controller-operator-history
- **controller_controls_mine:** Montana Materials LLC → Portable Crusher; 1995-04-11 to 1998-05-14; source msha-controller-operator-history
- **controller_controls_operator:** Montana Materials LLC → Montana Materials Llc; 1995-04-11 to 1998-05-14; source msha-controller-operator-history
- **operator_operates_mine:** Hollow Contracting Inc → Portable Crusher; 1998-05-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William J  Hollow → Hollow Contracting Inc; 1998-05-15 to current/open; source msha-controller-operator-history