We believe that Fred moved to the office. It is impossible that Brian is a swan. It is likely that Sandra is in the kitchen. We doubt that if 'Fred moved to the office' or 'Brian is a swan' or both then Gertrude is a sheep. It is likely that if either 'Fred moved to the office' or 'Brian is a swan' but not both then Bernhard is a rhino. Chances are about even that if 'Sandra is in the kitchen and Fred moved to the office' then Lily is yellow.
There is almost no chance that 'Bernhard is a rhino' or 'Brian is a swan' or both.
Chances are about even that 'Bernhard is a rhino' or 'Brian is a swan' or both.
There is almost no chance that 'Bernhard is a rhino' or 'Brian 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
  0.75::factA.
  0.0::factB.
  0.7::factC.
  %hop1
  0.2::factX:-or(factA,factB).
  0.7::factY:-xor(factA,factB).
  0.5::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Bernhard is a rhino' or 'Brian is a swan' or both.