We believe that Mary dropped the apple. There is little chance that John took the football. It is certain that Winona is a mouse. It is probably the case that if either 'Winona is a mouse' or 'Mary dropped the apple' but not both then Greg is a rhino. It is likely that if either 'Winona is a mouse' or 'Mary dropped the apple' but not both then Bernhard is a lion. It is probable that if 'John took the football' or 'Winona is a mouse' or both then Julius is yellow.
It is probably not the case that 'Greg is a rhino' or 'John took the football' or both.
It is probably not the case that 'Greg is a rhino' or 'John took the football' or both.
It is probable that 'Greg is a rhino' or 'John 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
  0.75::factA.
  0.1::factB.
  1.0::factC.
  %hop1
  0.7::factX:-xor(factC,factA).
  0.7::factY:-xor(factC,factA).
  0.7::factZ:-or(factB,factC).

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

  query(conclusion).
  
'Greg is a rhino' or 'John took the football' or both.