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 vickers machine gun (also known as the vickers gun) was a machine gun that was used by the british army from 1912 to 1968.

SOLUTION: vickers machine gun

PROBLEM: louise leakey (born 21 march 1972) is a kenyan paleontologist.

SOLUTION: louise leakey

PROBLEM: thallium(i) iodide, also known as thallous iodide, is a chemical compound.

SOLUTION:
thallium(i) iodide