It is highly likely that Julius is a lion. We doubt that Fred dropped the milk. There is little chance that Mary went to the hallway. There is little chance that if 'Mary went to the hallway and Julius is a lion' then Jason is thirsty. We believe that if 'Julius is a lion and Mary went to the hallway' then Brian is white. It is highly likely that if 'Fred dropped the milk' or 'Julius is a lion' or both then John grabbed the apple.
There is almost no chance that either 'Mary went to the hallway' or 'Brian is white' but not both.
There is almost no chance that either 'Mary went to the hallway' or 'Brian is white' but not both.
It is likely that either 'Mary went to the hallway' or 'Brian is white' 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
  0.9::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.1::factX:-and(factC,factA).
  0.75::factY:-and(factA,factC).
  0.9::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Mary went to the hallway' or 'Brian is white' but not both.