It is probable that Julius is a rhino. It is probably the case that John picked up the apple. It is certain that Bernhard is a frog. There is a better than even chance that if either 'Bernhard is a frog' or 'Julius is a rhino' but not both then Winona is a sheep. It is probably the case that if either 'Bernhard is a frog' or 'John picked up the apple' but not both then Yann is hungry. It is probable that if 'John picked up the apple and Bernhard is a frog' then Mary left the football.
It is improbable that 'Mary left the football' or 'Winona is a sheep' or both.
There is a better than even chance that 'Mary left the football' or 'Winona is a sheep' or both.
It is improbable 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
  0.7::factA.
  0.7::factB.
  1.0::factC.
  %hop1
  0.6::factX:-xor(factC,factA).
  0.7::factY:-xor(factC,factB).
  0.7::factZ:-and(factB,factC).

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

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