There is a very good chance that John left the football. It is certain that Greg is a frog. It is probably the case that Bernhard is white. It is impossible that if either 'Greg is a frog' or 'John left the football' but not both then Daniel dropped the apple. Chances are slight that if 'Bernhard is white' or 'John left the football' or both then Julius is green. It is probably not the case that if either 'John left the football' or 'Greg is a frog' but not both then Jason is tired.
There is a very good chance that 'Daniel dropped the apple' or 'John left the football' or both.
There is a very good chance that 'Daniel dropped the apple' or 'John left the football' or both.
It is improbable that 'Daniel dropped the apple' or 'John left 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
  0.8::factA.
  1.0::factB.
  0.7::factC.
  %hop1
  0.0::factX:-xor(factB,factA).
  0.1::factY:-or(factC,factA).
  0.25::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Daniel dropped the apple' or 'John left the football' or both.