It is probably the case that Julius is gray. There is almost no chance that Mary went to the office. There is little chance that Brian is a rhino. We doubt that if either 'Mary went to the office' or 'Julius is gray' but not both then Lily is a lion. It is probably not the case that if 'Mary went to the office' or 'Julius is gray' or both then Emily is a mouse. It is highly likely that if 'Julius is gray' or 'Brian is a rhino' or both then Bernhard is a frog.
There is a very good chance that 'Bernhard is a frog and Emily is a mouse'.
It is unlikely that 'Bernhard is a frog and Emily is a mouse'.
There is a very good chance that 'Bernhard is a frog and Emily is a mouse'.

  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
  0.7::factA.
  0.02::factB.
  0.1::factC.
  %hop1
  0.2::factX:-xor(factB,factA).
  0.25::factY:-or(factB,factA).
  0.9::factZ:-or(factA,factC).

  %hop2
  conclusion:-and(factZ,factY).

  query(conclusion).
  
'Bernhard is a frog and Emily is a mouse'.