VDB Properties - lambda-land/VDBMS GitHub Wiki
- if
p_t and p_R -> p_A and p_Rholds, then the value of attributeAin relationRof tupletcannot be irrelevant value (represented by null value right now)
p_t and p_R -> p_A and p_R holds, then the value of attribute A in relation R of tuple t cannot be irrelevant value (represented by null value right now)