It is unlikely that John put down the apple. It is probably the case that Bernhard is a swan. There is little chance that Mary dropped the milk. There is a very good chance that if 'John put down the apple and Mary dropped the milk' then Jessica is a mouse. It is almost certain that if either 'Mary dropped the milk' or 'John put down the apple' but not both then Greg is yellow. It is likely that if either 'John put down the apple' or 'Bernhard is a swan' but not both then Lily is white.
There is little chance that 'Jessica is a mouse' or 'Mary dropped the milk' or both.
There is little chance that 'Jessica is a mouse' or 'Mary dropped the milk' or both.
It is certain that 'Jessica is a mouse' or 'Mary dropped the milk' 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.
  0.1::factC.
  %hop1
  0.8::factX:-and(factA,factC).
  0.95::factY:-xor(factC,factA).
  0.7::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Jessica is a mouse' or 'Mary dropped the milk' or both.