rule+of+action
131Missing in action — This article is about the military term. For other uses, see Missing in action (disambiguation). Grave of an unknown British soldier killed during the Battle of Leros. Because his identity is unknown, he is missing in action …
132Semigroup action — In algebra and theoretical computer science, an action or act of a semigroup on a set is a rule which associates to each element of the semigroup a transformation of the set in such a way that the product of two elements of the semigroup (using… …
