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Using Armstrong’s axioms of functional dependency derive the following rules:

$\{ x \rightarrow y, \: x \rightarrow z \} = x \rightarrow yz$

(Note: $x \rightarrow y$ denotes $y$ is functionally dependenet on $x$, $z \subseteq y$ denotes $z$ is subset of $y$, and $\mid =$ means derives).