# Problems from the CYC Review

## Vaughan Pratt Stanford University April 16, 1994, Revised April 19, 1994

These are the elementary commonsense problems from my review of the Cyc project on April 15, 1994. --Vaughan Pratt
```1. Identity
(b)	How big are you?
(c)	How old are you?
(d)	What do you cost?

2. Counting
(a)	Do you understand counting?
(b)	What is the smallest counting number?
(c)	What is the largest counting number?
(d)	How high can you count?
(e)	How long would that take?
(f)	What other kinds of numbers are there besides counting numbers?

3. Comparison
(a)	Do you understand comparison?
(b)	If a is bigger than b and b is bigger than c, is a bigger than c?
(c)	If a is better than b and b is better than c, is a better than c?
(d)	If a is to the left of b and b is to the left of c, is a to the
left of c?
(e)	If Tom is 3 inches taller than Dick, and Dick is 2 inches taller than
Harry, how much taller is Tom than Harry?
(f)	Can Tom be taller than himself?
(g)	Can Tom be shorter than Dick?
(h)	Can a sister be taller than her brother?
(i)	Can two siblings each be taller than the other?

4. Geography
(a)	Where is the north pole?
(b)	What is the top of the earth called?
(c)	On a map, which compass direction is usually left?
(d)	Which compass direction is usually up?
(e)	How far north can one go?  How far west?
(f)	Is the equator between the north and south poles?
(g)	What shape is the earth?
(h)	Is the earth hollow?
(i)	What shape is the equator?
(j)	What shape is the north pole?
(k)	Which is wetter, land or sea?
(l)	How big is the earth?
(m)	How far apart are the poles?
(n)	What is the circumference of the equator?
(o)	If a is to the west of b and b is to the west of c, is a
necessarily to the west of c?

5. Travel
(a)	If Stanford is 50 miles from Berkeley, how far is Berkeley from
Stanford?
(b)	How far is Stanford from Stanford?
(c)	Can Stanford be 50 miles from Berkeley, Berkeley 50 miles from
Sacramento, and Stanford 1000 miles from Sacramento?
(d)	Is it possible to travel 100 miles and end up where you started?
(e)	While travelling at a steady speed in a straight line in space,
can you visit the same point twice?  Three times?
(f)	While travelling at a steady speed around a circle, can you visit
the same point twice?  Three times?

6. Action
(a)	Can people run?  Swim?  Fly?
(b)	Can fish run?  Swim?  Fly?
(c)	Can birds run?  Swim?  Fly?
(d)	Do people run on land or in water?  How about fish?  Birds?
(e)	Do people swim on land or in water?  How about fish?  Birds?
(f)	Do people fly on land or in the air?  How about fish?  Birds?
(g)	Which of legs, fins, and wings does one use to swim, run, and fly?
(h)	Which is fastest, swimming, running, or flying?  Which is slowest?
(i)	If the door is closed, what must you do first before walking
through it?
(j)	If the door is locked, what must you do first before opening it?
(k)	If the key is in your pocket, what must you do first before unlocking
the door?
(l)	What should I ask next?
(m)	If it takes all your energy to open the door, can you then walk
through it?

7. Transport
(a)	Which of cars, ships, and planes does one use to go by sea, land,
and air?
(b)	Which is fastest, cars, ships, or planes?  Which is slowest?
(c)	Which of cars, ships, and planes can carry cargo?  Which can
carry passengers?
(d)	Which was invented first, cars, ships, or planes?  Which last?
(e)	Which of cars, ships, and planes travel in shipping lanes, on
(f)	Match up cars, ships, and planes to the navy, army, and air force.
(g)	Is a jeep a car, a ship, or a plane?  What about a yacht?  A biplane?
An aircraft carrier?  A truck?
(h)	What fuels are normally used by cars, ships, and planes?
(i)	Can cars be propelled by the wind?  Ships?  Planes?
(j)	How do you communicate between two ships?  Two planes?  Two cars?
(k)	Can a plane communicate with a ship?  A plane with a car?
(l)	Where are cars kept when not in use?  Planes?  Ships?
(m)	What do you steer a car with?  What about a plane?  A ship?
(n)	Must a car always stop when driving through a small town?
(o)	Can a car drive backwards?  Can a plane fly backwards?  Can a
ship sail backwards?

8. Sky
(a)	What color is the sky?  Why?
(b)	What color are clouds?  Why?
(c)	What is the name of the period during which the sun is down?
(d)	What is the name of the period during which the sun is up?
(e)	Approximately when does the sun rise?
(f)	Give three names for the rising of the sun.
(g)	About how long does the sun stay up?
(h)	Approximately when does the sun set?
(i)	Give three names for the setting of the sun.
(k)	About how long does the sun stay down?
(l)	What are the times of rising and setting of the moon called?
(m)	How long does the moon stay up?
(n)	When do the stars come out?  Why?
(o)	Which is brightest, the sun, the moon, or the stars?  Which least?
(p)	Can you see the stars when the sun is up?
(q)	Can you see the moon when the sun is up?
(r)	Does the sun go round the earth or vice versa?
(s)	Does the moon go round the earth or vice versa?
(t)	Which is closer to the earth, the stars or the planets?

9. Weather
(a)	Is rain wet or dry?
(b)	Is hail hard or soft?
(c)	What color is rain?
(d)	What color is hail?
(e)	What color is snow?
(f)	Which is harder, rain or hail?
(g)	Which is warmer, rain or snow?
(h)	Can rain cause lightning?
(i)	Can rain cause floods?
(j)	Can lightning cause floods?

10. People
(a)	Can people walk?  Run?  Fly?  Swim?  Talk?  Think?
(b)	Name three external human organs and three internal.
(c)	How long can people go without air?  Water?  Food?  Sex?  Money?  Snow?
(d)	How long does the average human live?
(e)	Does the average female live more than a year longer than the
average male?
(f)	How tall is the average human?
(g)	Is the average male height within an inch of the average female height?
(h)	How heavy is the average human?
(i)	Is the average male weight within 5 lbs of the average female weight?
(j)	Are people made up mainly of organic or inorganic material?
(k)	Do people have more or less hair than polar bears?  Birds?  Pigs?
(l)	About how many people fit comfortably in a car?  A ship?  A plane?
An elevator?  An escalator?  A turnstile?
(m)	Do people talk daily about the weather?  The color of rain?
(n)	Can three people listen to the same person at the same time?
(o)	Can three people talk to the same person at the same time?
(p)	Can a person whistle while talking?

(b)	What is 1 plus 1?
(c)	What is 2 plus zero?
(d)	Is the sum of two counting numbers always a counting number?
(e)	Is every counting number the sum of two other counting numbers?
(g)	Does addition satisfy any other laws?
(h)	If I increment x y times, do I get the same as when I increment
y x times?
(i)	Can any two numbers be added together?

12. Lists
(a)	How long is the list of numbers from 1 to 10?
(b)	What comes between the third and fifth members of a list?
(c)	Do you know what it means to concatenate two lists?
(d)	What do you get when you concatenate the list of numbers from 1
to 3 with itself?
(e)	Is the concatenation of two lists always a list?
(f)	Is concatenation associative?
(g)	Is concatenation commutative?
(h)	How long is the concatenation of two three-item lists?
(i)	How long is the concatenation of two n-item lists?
(j)	Can a list be circular?
(k)	Is a list one-dimensional or two-dimensional?
(l)	Is a one-dimensional array a list?
(m)	Is the concatenation of a sorted list of 1-digit numbers with a
sorted list of 2-digit numbers sorted?
(n)	If the first two members of a list are both 1, and thereafter
each member is the sum of the two members immediately preceding
it, what is the third member?  The fourth?  The hundredth?

13. Subtraction
(a)	Do you understand subtraction?
(b)	What is 5 minus 3?
(c)	What is -3 plus 5?
(d)	If I open a bank account with \$100, deposit \$5000 a week later,
and withdraw \$3000 another week later, how much is in the account?
(e)	Do banks permit withdrawals from an empty account?
(f)	If I open a bank account with \$100, withdraw \$3000 a week later, and
the deposit \$5000 another week later, how much is in the account?
(g)	If I have \$x in my bank account and withdraw \$y, how much is left?
(h)	Can one withdraw a negative amount?  What would that mean?
(i)	Can I make two consecutive deposits?
(j)	Can I make any number of consecutive deposits?
(k)	Can I make two consecutive withdrawals?
(l)	Can I make any number of consecutive withdrawals?  What if they
are all negative?

14. Government
(a)	What is the name of the head of a monarchy?  A dictatorship?
A republic?  How is each typically chosen?
(b)	How long does a major election take, seconds, months, or decades?
(c)	Is an election candidate who gets 90% of the votes likely to
win his or her race?  How about 80%?  20%?  10%?
(d)	What are the two best known ways of getting votes, from among