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.

[EX Q]: sir john soane (10 september 1753 – 20 january 1837) was an english architect.
[EX A]: john soane

[EX Q]: goldhanger is a village and civil parish in maldon district, essex, england.
[EX A]: goldhanger

[EX Q]: in mathematics, the cartesian coordinate system is a coordinate system used to place points on a plane using two numbers, usually called the "x-coordinate" and the "y-coordinate".
[EX A]:
cartesian coordinate system