6.12

Consider the following lattice structure of generalization and specialization (attributes are not shown).

For entity sets \(A\), \(B\), and \(C\), explain how attributes are inherited from the higher level entity sets \(X\) and \(Y\). Discuss how to handle a case where an attribute of \(X\) has the same name as some attribute of \(Y\).

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\(A\) inherits all the attributes of \(X\), plus it may define its own attributes. Similarly, \(C\) inherits all the attributes of \(Y\) plus its own attributes. \(B\) inherits the attributes of both \(X\) and \(Y\). If there is some attribute name which belongs to both \(X\) and \(Y\), it may be referred to in \(B\) by the qualified name \(X\)._name_ or \(Y\)._name_.