赖绵县 Non-RE Languages Lemma:the set of all languages is uncountable Suppose we could enumerate all languages over {0,l}and talk about“thei-th language..” Consider the language L={ww is the i-th binary string and w is not in the i-th languageNon-RE Languages ◼ Lemma: the set of all languages is uncountable ◼ Suppose we could enumerate all languages over {0,1} and talk about “the i-th language.” ◼ Consider the language L = { w | w is the i-th binary string and w is not in the i-th language}