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 british rail class 931 was reserved for former southern region electrical multiple units converted for departmental use.

SOLUTION: british rail class 931

PROBLEM: pablo escobar and his brother's school once sent them home because they had no shoes and no money to buy them.

SOLUTION: pablo escobar

PROBLEM: franz joseph ii, prince of liechtenstein ("franz josef maria aloys alfred karl johannes heinrich michael georg ignaz benediktus gerhardus majella"; 16 august 1906 – 13 november 1989) was the prince of liechtenstein from 1938 until his death.

SOLUTION:
franz joseph ii, prince of liechtenstein