MEU and VPI
Formulas

Independence Properties
- If node and UtilityNode are D-separated (no active path / cond. ind), VPI(node) = 0
- If they are not cond. ind. then they could either be ind. or dep. and therefore it is possible that VPI(node) ≥ 0
- If two non-utility nodes are ind. then VPI(one node | their parent) = 0