KR: Exercise 3

Probabilistic Reasoning with Answer Sets

Rock, paper and scissors


John and Mary are playing the popular game "rock, paper and scissors". We suppose that each of them selects one sign in a completely random way, equally probable for the three cases. Rock wins to scissors, scissors wins to paper and paper wins to rock.

What to do

Model the scenario in P-log so that we can conclude any of the facts, winner(mary), winner(john) or tie, according to the game result. Then, compute with P-log the following probabilites
  • The probability of winner(mary).
  • The probability of winner(mary) conditioned to the observation play(john)=rock.
  • The probability of a  tie.

Now suppose that Mary is sometimes quick enough to see John making the "paper" sign. In fact, 2 of each 3 times, she is able to foresee John's "paper" and so, she marks "scissors". Model this variant and recompute the three probabilities above in this new situation.

You must deliver three files: two files with the domains in P-log (the original one and the second variant) plus a text file listing the obtained results (and, if possible, explaining their values).

Assessment & delivery

The maximum grade for this exercise is 0,5 points. The deadline for delivery is May 31th, 2013 using the lab work mailbox or buzón de prácticas.

Maintained by Pedro Cabalar. Last update May. 9th 2013