It is likely that Sandra dropped the milk. It is probably the case that Greg is a swan. It is highly likely that Brian is yellow. We doubt that if either 'Greg is a swan' or 'Brian is yellow' but not both then Jessica is a mouse. It is probably the case that if 'Greg is a swan and Brian is yellow' then Daniel left the milk. We believe that if either 'Greg is a swan' or 'Brian is yellow' but not both then Lily is a rhino.
It is impossible that 'Brian is yellow' or 'Jessica is a mouse' or both.
It is highly likely that 'Brian is yellow' or 'Jessica is a mouse' or both.
It is impossible that 'Brian is yellow' or 'Jessica is a mouse' 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.
  0.7::factB.
  0.9::factC.
  %hop1
  0.2::factX:-xor(factB,factC).
  0.7::factY:-and(factB,factC).
  0.75::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Brian is yellow' or 'Jessica is a mouse' or both.