There is almost no chance that John grabbed the apple. There is little chance that Gertrude is a sheep. It is probably the case that Emily is a wolf. It is likely that if 'Gertrude is a sheep and John grabbed the apple' then Lily is a frog. It is unlikely that if 'Gertrude is a sheep and John grabbed the apple' then Mary went to the kitchen. We doubt that if 'Emily is a wolf and John grabbed the apple' then Brian is a lion.
There is a very good chance that 'Brian is a lion' or 'John grabbed the apple' or both.
There is almost no chance that 'Brian is a lion' or 'John grabbed the apple' or both.
There is a very good chance that 'Brian is a lion' or 'John grabbed 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
  0.02::factA.
  0.1::factB.
  0.7::factC.
  %hop1
  0.7::factX:-and(factB,factA).
  0.2::factY:-and(factB,factA).
  0.2::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Brian is a lion' or 'John grabbed the apple' or both.