/*
Here follows an incorrect test item found in a published collection.

Every brown hair person is an employee.  Alfonso likes level roads.
People who like level roads have brown hair.
Select the statement that is certainly true:

A. Every employee likes level roads
B. Alfonso is an employee
C. Every brown hair person likes level roads
D. Alfonso has brown hair

The booklet points out A as the correct answer.  This is not 
just a typing error: not only is A not derivable, but both B and D are
logical consequences of the stem.
*/

Types: person.
Predicates: brown_hair(person) employee(person)
            likes_level_roads(person).
Objects: alfonso bernardo: person. 
## Attention: whenever we want to check the truth of a universal
## assertion, the domain cannot be limited to the objects named
## in the test

Theory:
  forall x:person(brown_hair(x) -> employee(x)),
  likes_level_roads(alfonso),
  forall x:person (likes_level_roads(x) -> brown_hair(x)).

Deduce:  
  forall x:person (employee(x) -> likes_level_roads(x)),
  employee(alfonso),
  forall x:person (brown_hair(x) -> likes_level_roads(x)),
  brown_hair(alfonso).