7.26

Consider the following proposed rule for functional dependencies: If \(\alpha \rightarrow \beta\) and \(\gamma \rightarrow \beta\), then \(\alpha \rightarrow \gamma\). Prove that this rule is not sound by showing a relation r that satisfies \(\alpha \rightarrow \beta\) and \(\gamma \rightarrow \beta\), but does not satisfy \(\alpha \rightarrow \gamma\).

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\(\alpha\)	\(\gamma\)	\(\beta\)
1	6	7
2	3	5
2	4	5