The following story from the New York Times is my candidate for a target for a natural language understander. The story is about a real world event, and therefore the intentions of the author are less relevant for answering questions than for made up stories. The main goal of this discussion is to say what a person who has understood the story knows about the event. This seems to me to be preliminary to making programs that can understand.
``A 61-year old furniture salesman was pushed down the shaft of a freight elevator yesterday in his downtown Brooklyn store by two robbers while a third attempted to crush him with the elevator car because they were dissatisfied with the $1,200 they had forced him to give them.
The buffer springs at the bottom of the shaft prevented the car from crushing the salesman, John J. Hug, after he was pushed from the first floor to the basement. The car stopped about 12 inches above him as he flattened himself at the bottom of the pit.
Mr. Hug was pinned in the shaft for about half an hour until his cries attracted the attention of a porter. The store at 340 Livingston Street is part of the Seaman's Quality Furniture chain.
Mr. Hug was removed by members of the Police Emergency Squad and taken to Long Island College Hospital. He was badly shaken, but after being treated for scrapes of his left arm and for a spinal injury was released and went home. He lives at 62-01 69th Lane, Maspeth, Queens.
He has worked for seven years at the store, on the corner of Nevins Street, and this was the fourth time he had been held up in the store. The last time was about one year ago, when his right arm was slashed by a knife-wielding robber.''
An intelligent person or program should be able to answer the following questions based on the information in the story:
1. Who was in the store when the events began? Probably Mr. Hug alone. although the robbers might have been waiting for him, but if so, this would have probably been stated. What did the porter say to the robbers? Nothing, because the robbers left before he came.
2. Who was in the store during the attempt to kill Mr. Hug? Mr. Hug and the robbers.
3. Who had the money at the end? The robbers.
4. Is Mr. Hug alive today? Yes, unless something else has happened to him.
5. How did Mr. Hug get hurt? Probably when he hit the bottom of the shaft.
6. Where is Mr. Hug's home? (A question whose answer requires a literal understanding of only one sentence of the story.) Does Mr. Hug live in Brooklyn? No, he lives in Queens.
7. What are the names and addresses of the robbers? This information is not available.
8. Was Mr. Hug conscious after the robbers left? Yes, he cried out and his cries were heard.
9. What would have happened if Mr. Hug had not flattened himself at the bottom of the pit? What would have happened if there were no buffer springs? Mr. Hug would have been crushed.
10. Did Mr. Hug want to be crushed? No.
11. Did the robbers tell Mr. Hug their names? No.
12. Were the robbers present when the porter came? No.
13. Did Mr. Hug like the robbers, and did they like him?
14. Why did the robbers leave without killing Mr. Hug? Perhaps, they thought they had killed him, and perhaps their anger was appeased by the actions they had performed, and perhaps they had taken all the time they dared, and perhaps something specific happened to frighten them away.
15. What would have happened if Mr. Hug had tried to run away? Perhaps he would have succeeded, but more likely they would have injured or killed him since probably they had weapons, and there were three of them.
16. What can Mr. Hug do to avoid this in the future? No solution is entirely satisfactory. He could carry a gun or he could quit or he could get his employers to install an alarm system or maybe he will be lucky.
17. Did Mr. Hug know he was going to be robbed? Does he know that he was robbed?
18. Was Mr. Hug's right arm slashed before his left arm was scratched? Yes, because the former was a year ago.
19. How did the robber try to crush him with the car? By pressing the buttons or operating the control lever to make the car go to the bottom of the shaft.
20. Why did Mr. Hug yell from the bottom of the elevator shaft? So as to attract the attention of someone who would rescue him.
21. How long did the events take? More than half an hour but less than a day. Most of the time was spent by Mr. Hug filling out forms in the hospital.
22. What crimes were committed? This question has the advantage that it is one that is normally answered on the basis of such a story, since the police report of the incident was probably the basis of the New York Times story. Robbery, possibly assault with a deadly weapon, and attempted murder are the more obvious crimes. One might specifically challenge natural language systems to answer this question.
The above list of questions is rather random. I doubt that it covers all facets of understanding the story. It would be worthwhile to try to make up a list of questions that does cover substantially all aspects of the story in order to get as complete as possible an intuitive idea of what capabilities are involved in understanding such a story.
Note that the story is about a real event so that such a question as what does the ``J'' in ``John J. Hug'' stand for has an answer. In a made-up story, questions about middle names or what year the story occurred in do not necessarily have an answer, and an intelligent person or program would know that too.