# Relationship history for MSHA mine 2901732

Current hierarchy: **Bill B  Armstrong Jr → Armstrong & Armstrong → Carrasco 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Armstrong & Armstrong → Carrasco Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bill B  Armstrong Jr  et al → Carrasco Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bill B  Armstrong Jr  et al → Armstrong & Armstrong; 1979-01-01 to current/open; source msha-controller-operator-history