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.

srivilliputhur taluk is a taluk of virudhunagar district of the indian state of tamil nadu.
srivilliputhur taluk

the river clyde (, ]) is a river in scotland.
river clyde

the chinese postman problem is a mathematical problem of graph theory.

chinese postman problem