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 [[!toc]]
 
+#Recursion: fixed points in the lambda calculus##
+
+Sometimes when you type in a web search, Google will suggest
+alternatives.  For instance, if you type in "Lingusitics", it will ask
+you "Did you mean Linguistics?".  But the engineers at Google have
+added some playfulness to the system.  For instance, if you search for
+"anagram", Google asks you "Did you mean: nag a ram?"  And if you
+search for "recursion", Google asks: "Did you mean: recursion?"
+
 ##What is the "rec" part of "letrec" doing?##
 
 How could we compute the length of a list? Without worrying yet about what lambda-calculus implementation we're using for the list, the basic idea would be to define this recursively: