It is probably not the case that Emily is a sheep. It is highly likely that Daniel left the milk. There is a better than even chance that Mary dropped the milk. Chances are about even that if 'Mary dropped the milk and Daniel left the milk' then Greg is a rhino. There is a very good chance that if 'Mary dropped the milk and Daniel left the milk' then Winona is a wolf. It is improbable that if 'Daniel left the milk' or 'Emily is a sheep' or both then John put down the apple.
It is certain that 'Greg is a rhino' or 'Emily is a sheep' or both.
Chances are about even that 'Greg is a rhino' or 'Emily is a sheep' or both.
It is certain that 'Greg is a rhino' or 'Emily is a sheep' 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
  0.25::factA.
  0.9::factB.
  0.6::factC.
  %hop1
  0.5::factX:-and(factC,factB).
  0.8::factY:-and(factC,factB).
  0.1::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Greg is a rhino' or 'Emily is a sheep' or both.