It is certain that Sandra dropped the milk. It is impossible that Greg is a rhino. It is almost certain that Fred is in the office. It is unlikely that if 'Sandra dropped the milk' or 'Greg is a rhino' or both then Mary took the football. It is probably the case that if 'Sandra dropped the milk and Greg is a rhino' then Bernhard is a lion. It is unlikely that if 'Sandra dropped the milk and Greg is a rhino' then Gertrude is a mouse.
It is almost certain that 'Fred is in the office' or 'Mary took the football' or both.
It is almost certain that 'Fred is in the office' or 'Mary took the football' or both.
It is unlikely that 'Fred is in the office' or 'Mary took the football' 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
  1.0::factA.
  0.0::factB.
  0.95::factC.
  %hop1
  0.2::factX:-or(factA,factB).
  0.7::factY:-and(factA,factB).
  0.2::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Fred is in the office' or 'Mary took the football' or both.