It is unlikely that Jessica is a mouse. It is probably the case that Bernhard is a frog. It is likely that Brian is gray. It is likely that if 'Bernhard is a frog and Jessica is a mouse' then Jeff moved to the garden. It is likely that if 'Brian is gray' or 'Bernhard is a frog' or both then Mary grabbed the milk. Chances are about even that if either 'Bernhard is a frog' or 'Jessica is a mouse' but not both then Julius is a swan.
We doubt that 'Bernhard is a frog' or 'Julius is a swan' or both.
We believe that 'Bernhard is a frog' or 'Julius is a swan' or both.
We doubt that 'Bernhard is a frog' or 'Julius is a swan' or 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
  0.2::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.7::factX:-and(factB,factA).
  0.7::factY:-or(factC,factB).
  0.5::factZ:-xor(factB,factA).

  %hop2
  conclusion:-or(factB,factZ).

  query(conclusion).
  
'Bernhard is a frog' or 'Julius is a swan' or both.