There is little chance that Brian is a rhino. There is almost no chance that Lily is green. Chances are slight that Yann is tired. There is a very good chance that if either 'Yann is tired' or 'Brian is a rhino' but not both then Mary took the football. It is impossible that if either 'Yann is tired' or 'Brian is a rhino' but not both then Julius is a frog. It is likely that if 'Brian is a rhino' or 'Lily is green' or both then John dropped the apple.
It is highly likely that 'Lily is green' or 'John dropped the apple' or both.
Chances are slight that 'Lily is green' or 'John dropped the apple' or both.
It is highly likely that 'Lily is green' or 'John dropped the apple' 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
  0.1::factA.
  0.02::factB.
  0.1::factC.
  %hop1
  0.8::factX:-xor(factC,factA).
  0.0::factY:-xor(factC,factA).
  0.7::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Lily is green' or 'John dropped the apple' or both.