The monkey-and-bananas problem is faced by a monkey in a laboratory with some
bananas hanging out of reach from the ceiling. A box is available that will enable the monkey
to reach the bananas if he climbs on it. Initially, the monkey is at A, the bananas at B, and the
box at C . The monkey and box have height Low , but if the monkey climbs onto the box he
will have height High , the same as the bananas. The actions available to the monkey include
Go from one place to another, Push an object from one place to another, ClimbUp onto or ClimbDown from an object, and Grasp or Ungrasp an object. Grasping results in holding
the object if the monkey and object are in the same place at the same height.
a. Write down the initial state description.
b. Write down STRIPS-style deﬁnitions of the six actions.
c. Suppose the monkey wants to fool the scientists, who are off to tea, by grabbing the
bananas, but leaving the box in its original place. Write this as a general goal (i.e., not
assuming that the box is necessarily at C) in the language of situation calculus. Can this
goal be solved by a S T R I P S-style system?
d. Your axiom for pushing is probably incorrect, because if the object is too heavy, its
position will remain the same when the Push operator is applied. Is this an example of
the ramiﬁcation problem or the qualiﬁcation problem? Fix your problem description to
account for heavy objects.
(From Russel and Norvig, ch 11: available on-line)