Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
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Question: police action is a term for the use of military forces without declaring war.

Answer: police action


Question: euclid's lemma, also called euclid's division lemma or euclid's first theorem, is an important lemma.

Answer: euclid's lemma


Question: caroline esmeralda van der leeuw (born 26 april 1981), best known by her stage name of caro emerald, is a dutch pop and jazz singer.

Answer:
caro emerald