There is little chance that Mary dropped the apple. It is almost certain that Lily is a lion. Chances are about even that John took the football. It is highly unlikely that if 'John took the football and Mary dropped the apple' then Greg is yellow. It is almost certain that if either 'Lily is a lion' or 'John took the football' but not both then Gertrude is a mouse. It is likely that if either 'John took the football' or 'Lily is a lion' but not both then Bernhard is green.
We doubt that 'Bernhard is green' or 'Lily is a lion' or both.
It is almost certain that 'Bernhard is green' or 'Lily is a lion' or both.
We doubt that 'Bernhard is green' or 'Lily is a lion' 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
  0.1::factA.
  0.95::factB.
  0.5::factC.
  %hop1
  0.05::factX:-and(factC,factA).
  0.95::factY:-xor(factB,factC).
  0.7::factZ:-xor(factC,factB).

  %hop2
  conclusion:-or(factZ,factB).

  query(conclusion).
  
'Bernhard is green' or 'Lily is a lion' or both.