We doubt that Lily is green. Chances are slight that Brian is a rhino. Chances are about even that Julius is white. We believe that if 'Lily is green and Julius is white' then John dropped the apple. It is probably the case that if 'Julius is white and Brian is a rhino' then Mary picked up the apple. We believe that if either 'Brian is a rhino' or 'Julius is white' but not both then Sandra took the football.
We doubt that 'Lily is green' or 'John dropped the apple' or both.
We doubt that 'Lily is green' or 'John dropped the apple' or both.
It is likely that 'Lily is green' or 'John dropped the apple' 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.
  0.1::factB.
  0.5::factC.
  %hop1
  0.75::factX:-and(factA,factC).
  0.7::factY:-and(factC,factB).
  0.75::factZ:-xor(factB,factC).

  %hop2
  conclusion:-or(factA,factX).

  query(conclusion).
  
'Lily is green' or 'John dropped the apple' or both.