Zebra Problem

1
Zebra Problem
The problem Who Owns the Zebra is a classic
problem in logical deduction. The elements of
the problem require you to identify each item
with a house.

• House
• Beverage
• Color
• Nationality
• Pet
• Occupation

2
COT-3100 Zebra Problem

• Who owns the zebra? attributed to Albert
  Einstein.
• Five men of different nationalities, with
  different jobs, live in consecutive houses on a
  street. These houses are painted different
  colors. The men have different pets and have
  different favorite drinks.
• Determine who owns the zebra and whose favorite
  drink is mineral water.
• Here are the clues
• The Englishman lives in the red house.
• The Spaniard owns a dog.
• The green house is on the right side of the white
  house.
• The Italian drinks tea.
• The Norwegian lives in the first house on the
  left.
• The photographer breeds snails.
• The Norwegians house is next to the blue one.
• The Japanese man is a painter.
• The fox is in a house next to that of the
  physician.
• The diplomat lives in the yellow house.
• The owner of the green house drinks coffee.
• The violinist drinks orange juice.
• The horse is in a house next to that of the
  diplomat.
• Milk is drunk in the middle house.

3
Zebra Problem

• House
• Beverage Coffee Milk O.J. Tea Water
• Color Blue Green Red White Yellow
• Nationality Englishman Italian Japanese
  Norwegian Spaniard
• Pet Dog Fox Horse Snail Zebra
• Occupation Painter Photographer Physican
  Diplomat Violinist

Each item is treated as an EXCLUSIVE OR within
its category
4
COT-3100 Zebra Problem
Symbolically representing the relationships, and
the NOT relationships
Violinist ?? O.J. Spaniard ?? Dog Japanese
??Painter Italian ?? Tea Norwegian ? House
1 White ? Green (R) Photographer ?? Snails
Norwegian ? Blue (next) Milk ?? House 3 Green ??
Coffee Yellow ?? Horse (next) Englishman ?? Red
House Physician ?? Fox (next) Diplomat ?? Horse
(next) Diplomat ?? Yellow
Spaniard ? Photographer Italian ? House
3 Englishman ? Coffee Englishman ?
Blue Englishman ? House 1/2 Japanese ?
Photo Italian ? Green Japanese ? Violinist
Blue ? House 2
5
COT-3100 Zebra Problem
Color Blue Green Red White Yellow
Nationality Englishman Italian Japanese
Norwegian Spaniard
Pet Dog Fox Horse Snail Zebra
Beverage Coffee Milk O.J. Tea Water
Occupation Painter Photographer Physician
Diplomat Violinist
6
COT-3100 Zebra Problem
Plotting known elements
Plotting elements that are eliminated from each
house
7
COT-3100 Zebra Problem
Results and/or possibilities (from eliminations)
Italian ? Violinist/Physician Spaniard ?
Violinist/Physician Englishman ?
Photographer
8
COT-3100 Zebra Problem
Spaniard ? Violinist ? O.J ? White
9
COT-3100 Zebra Problem
The ZEBRA problem is an excellent exercise in
logic flow.
It is also a 5 x 5 matrix, and makes an excellent
project for computer analysis.