It is probably not the case that Lily is a rhino. It is likely that John dropped the apple. It is probably the case that Sandra left the football. There is little chance that if 'Sandra left the football' or 'Lily is a rhino' or both then Greg is a lion. It is almost certain that if either 'Sandra left the football' or 'Lily is a rhino' but not both then Jeff went to the hallway. Chances are about even that if either 'John dropped the apple' or 'Lily is a rhino' but not both then Julius is a swan.
It is improbable that either 'John dropped the apple' or 'Lily is a rhino' but not both.
There is a better than even chance that either 'John dropped the apple' or 'Lily is a rhino' but not both.
It is improbable that either 'John dropped the apple' or 'Lily is a rhino' 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
  0.25::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.1::factX:-or(factC,factA).
  0.95::factY:-xor(factC,factA).
  0.5::factZ:-xor(factB,factA).

  %hop2
  conclusion:-xor(factB,factA).

  query(conclusion).
  
Either 'John dropped the apple' or 'Lily is a rhino' but not both.