It is likely that Bernhard is white. Chances are about even that Jason is thirsty. We doubt that Greg is a lion. It is probable that if 'Greg is a lion' or 'Bernhard is white' or both then Mary went to the kitchen. It is impossible that if either 'Greg is a lion' or 'Jason is thirsty' but not both then John dropped the milk. Chances are about even that if 'Jason is thirsty and Bernhard is white' then Daniel left the milk.
We believe that 'Bernhard is white' or 'Mary went to the kitchen' or both.
We believe that 'Bernhard is white' or 'Mary went to the kitchen' or both.
We doubt that 'Bernhard is white' or 'Mary went to the kitchen' 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
  0.7::factA.
  0.5::factB.
  0.2::factC.
  %hop1
  0.7::factX:-or(factC,factA).
  0.0::factY:-xor(factC,factB).
  0.5::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Bernhard is white' or 'Mary went to the kitchen' or both.