TASK DEFINITION: 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.
PROBLEM: the river clyde (, ]) is a river in scotland.

SOLUTION: river clyde

PROBLEM: corrosion is the breakdown of materials due to chemical reactions.

SOLUTION: corrosion

PROBLEM: keith richards (born 18 december 1943) is an english guitarist best known as a founder member of the rolling stones.

SOLUTION:
keith richards