Teorema 19.2.1.

Suatu latis \(L\) bersifat distributif jika dan hanya jika
\begin{equation*} a \vee ( b \wedge c ) = ( a \vee b ) \wedge ( a \vee c ) \end{equation*}
untuk semua \(a, b, c \in L\text{.}\)

Bukti.

Misalkan \(L\) merupakan latis distributif.
\begin{align*} a \vee ( b \wedge c ) & = [a \vee (a \wedge c) ] \vee ( b \wedge c )\\ & = a \vee [(a \wedge c) \vee ( b \wedge c )]\\ & = a \vee [(c \wedge a) \vee ( c \wedge b )]\\ & = a \vee [c \wedge ( a \vee b )]\\ & = a \vee [( a \vee b ) \wedge c ]\\ & = [( a \vee b ) \wedge a ] \vee [(a \vee b) \wedge c ]\\ & = ( a \vee b ) \wedge ( a \vee c )\text{.} \end{align*}
Arah sebaliknya langsung mengikuti Prinsip Dualitas.
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