Rewrite rule that applies associativity optimizations to simplify expressions.
See: https://en.wikipedia.org/wiki/Associative_property
Applies the transformations:
A OR (A OR B) = A OR BA OR B OR A = A OR BA AND (A AND B) = A AND BA AND B AND A = A AND B
The associativity optimizations leverage the associative property of boolean operations to eliminate redundant terms when the same expression appears multiple times in an associative context.