Chances are slight that Emily is a wolf. Chances are slight that Sumit is hungry. Chances are about even that Bernhard is a lion. It is improbable that if either 'Bernhard is a lion' or 'Sumit is hungry' but not both then Sandra dropped the milk. It is likely that if 'Bernhard is a lion' or 'Sumit is hungry' or both then John discarded the milk. There is a better than even chance that if 'Bernhard is a lion and Emily is a wolf' then Greg is a frog.
It is highly likely that either 'John discarded the milk' or 'Greg is a frog' but not both.
It is probably not the case that either 'John discarded the milk' or 'Greg is a frog' but not both.
It is highly likely that either 'John discarded the milk' or 'Greg is a frog' but not 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.
  0.1::factB.
  0.5::factC.
  %hop1
  0.1::factX:-xor(factC,factB).
  0.7::factY:-or(factC,factB).
  0.6::factZ:-and(factC,factA).

  %hop2
  conclusion:-xor(factY,factZ).

  query(conclusion).
  
Either 'John discarded the milk' or 'Greg is a frog' but not both.