It is certain that Jessica is a cat. It is probable that John went to the hallway. There is a very good chance that Brian is green. Chances are about even that if 'Brian is green and Jessica is a cat' then Daniel left the milk. There is a very good chance that if either 'Jessica is a cat' or 'John went to the hallway' but not both then Sandra dropped the milk. It is likely that if 'Brian is green and John went to the hallway' then Emily is a wolf.
Chances are about even that either 'Brian is green' or 'Emily is a wolf' but not both.
Chances are about even that either 'Brian is green' or 'Emily is a wolf' but not both.
It is highly unlikely that either 'Brian is green' or 'Emily is a wolf' but not both.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  1.0::factA.
  0.7::factB.
  0.8::factC.
  %hop1
  0.5::factX:-and(factC,factA).
  0.8::factY:-xor(factA,factB).
  0.7::factZ:-and(factC,factB).

  %hop2
  conclusion:-xor(factC,factZ).

  query(conclusion).
  
Either 'Brian is green' or 'Emily is a wolf' but not both.