It is likely that Bernhard is a swan. Chances are slight that Emily is a sheep. There is a very good chance that Greg is a frog. It is likely that if 'Greg is a frog and Bernhard is a swan' then Julius is white. There is little chance that if 'Emily is a sheep' or 'Bernhard is a swan' or both then Mary grabbed the milk. We doubt that if 'Emily is a sheep and Bernhard is a swan' then John went to the hallway.
There is a better than even chance that 'Greg is a frog and Bernhard is a swan'.
There is a better than even chance that 'Greg is a frog and Bernhard is a swan'.
There is little chance that 'Greg is a frog and Bernhard is a swan'.

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

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

  query(conclusion).
  
'Greg is a frog and Bernhard is a swan'.