There is little chance that John dropped the apple. There is almost no chance that Greg is yellow. It is probable that Jeff moved to the garden. We believe that if 'Jeff moved to the garden and John dropped the apple' then Jason is bored. It is certain that if 'Greg is yellow' or 'John dropped the apple' or both then Lily is a swan. It is highly likely that if either 'Jeff moved to the garden' or 'Greg is yellow' but not both then Bernhard is a lion.
It is improbable that 'John dropped the apple' or 'Jason is bored' or both.
It is improbable that 'John dropped the apple' or 'Jason is bored' or both.
It is likely that 'John dropped the apple' or 'Jason is bored' 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
  0.1::factA.
  0.02::factB.
  0.7::factC.
  %hop1
  0.75::factX:-and(factC,factA).
  1.0::factY:-or(factB,factA).
  0.9::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'John dropped the apple' or 'Jason is bored' or both.