Identify the subject in the following sentence: 'Kurt Vonnegut is a published author.'

The subject of the sentence "Kurt Vonnegut is a published author" is "Kurt Vonnegut." In this sentence, "Kurt Vonnegut" serves as the main noun that the sentence is about. The subject is what the sentence describes or provides information about. Here, it tells us who is being discussed—Kurt Vonnegut—and the predicate "is a published author" gives us information about him. The other components of the sentence do not serve as the subject; "a published author" is a predicate noun describing what Kurt Vonnegut is, "is" is the linking verb connecting the subject and predicate, and "a sentence" is a noun referring to the sentence itself, rather than part of the sentence's structure. Thus, identifying "Kurt Vonnegut" as the subject accurately reflects the grammatical role in the structure of the sentence.