- In mathematics, a binary operation is commutative if changing the order of the operands does not change the result.
- Associative property (Wikipedia)
In mathematics, the associative property is a property of some binary operations, which means that rearranging the parentheses in an expression will not change the result. In propositional logic, associativity is a valid rule of replacement for expressions in logical proofs.
- Spica (stars.astro.illinois.edu)
SPICA (Alpha Virginis). Spica, the luminary of Virgo, becomes prominent in the southeast in northern spring evenings, and can easily be found by following the curve of the Big Dipper’s handle through Arcturus and then on down.