It is certain that Sandra left the milk. There is a very good chance that Bernhard is a frog. It is probable that Gertrude is a sheep. It is unlikely that if 'Gertrude is a sheep' or 'Bernhard is a frog' or both then Brian is yellow. It is likely that if 'Bernhard is a frog' or 'Sandra left the milk' or both then Lily is a rhino. It is probable that if either 'Gertrude is a sheep' or 'Bernhard is a frog' but not both then Greg is a frog.
We doubt that 'Sandra left the milk and Brian is yellow'.
We doubt that 'Sandra left the milk and Brian is yellow'.
There is a very good chance that 'Sandra left the milk and Brian is yellow'.

  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
  1.0::factA.
  0.8::factB.
  0.7::factC.
  %hop1
  0.2::factX:-or(factC,factB).
  0.7::factY:-or(factB,factA).
  0.7::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'Sandra left the milk and Brian is yellow'.