olemus
binaartehe \(\ast\), mille korral kehtib
\(x \ast y = y \ast x\) mis tahes argumentidega \(x\) ja \(y\)
= an operation ∗ where a ∗ b = b ∗ a

ülevaateid
https://groupprops.subwiki.org/wiki/Commutative_binary_operation
https://en.wikipedia.org/wiki/Commutative_property