It is highly likely that Bernhard is yellow. It is likely that Sumit is thirsty. It is improbable that Winona is a sheep. There is little chance that if either 'Sumit is thirsty' or 'Bernhard is yellow' but not both then Brian is white. Chances are slight that if 'Sumit is thirsty' or 'Bernhard is yellow' or both then Mary left the football. It is unlikely that if either 'Winona is a sheep' or 'Bernhard is yellow' but not both then John took the apple.
There is a very good chance that 'Mary left the football' or 'Winona is a sheep' or both.
We doubt that 'Mary left the football' or 'Winona is a sheep' or both.
There is a very good chance that 'Mary left the football' or 'Winona 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
  0.9::factA.
  0.7::factB.
  0.1::factC.
  %hop1
  0.1::factX:-xor(factB,factA).
  0.1::factY:-or(factB,factA).
  0.2::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Mary left the football' or 'Winona is a sheep' or both.