Set Inclusion

$\textbf{Includes} \; A \; B$

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$A \in \textbf{Set}$

$B \in \textbf{Set}$

$\forall (x : x \in A : x \in B)$

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Notation

1. $A \subseteq B$ denotes $\textbf{Includes} \; A \; B$.

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pred Includes(A,B: set univ) {
  A in B
}