It is certain that Mary went to the office. There is little chance that Greg is a frog. There is almost no chance that Julius is a lion. It is highly unlikely that if 'Greg is a frog and Julius is a lion' then Emily is a sheep. There is almost no chance that if 'Julius is a lion' or 'Mary went to the office' or both then Brian is a rhino. It is unlikely that if 'Julius is a lion and Greg is a frog' then Jessica is a mouse.
There is almost no chance that either 'Jessica is a mouse' or 'Julius is a lion' but not both.
There is almost no chance that either 'Jessica is a mouse' or 'Julius is a lion' but not both.
It is certain that either 'Jessica is a mouse' or 'Julius is a lion' 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.
  0.1::factB.
  0.02::factC.
  %hop1
  0.05::factX:-and(factB,factC).
  0.02::factY:-or(factC,factA).
  0.2::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Jessica is a mouse' or 'Julius is a lion' but not both.