b. The set of linear functions f : X >B has a cardinality of 2n and is known as the "dual space" X* in vector space contexts. In formal language contexts, in order to avoid conflicts with the use of the "Kleene star" operator, it needs to be given an alternate notation: | b. The set of linear functions f : X >B has a cardinality of 2n and is known as the "dual space" X* in vector space contexts. In formal language contexts, in order to avoid conflicts with the use of the "Kleene star" operator, it needs to be given an alternate notation: |