We believe that Julius is a lion. There is a very good chance that Fred left the apple. It is impossible that Brian is a rhino. It is highly likely that if either 'Brian is a rhino' or 'Julius is a lion' but not both then Mary went to the bedroom. It is probably not the case that if 'Julius is a lion' or 'Brian is a rhino' or both then Greg is a frog. It is probable that if 'Fred left the apple and Julius is a lion' then John dropped the milk.
We doubt that 'Greg is a frog' or 'Julius is a lion' or both.
We believe that 'Greg is a frog' or 'Julius is a lion' or both.
We doubt that 'Greg is a frog' or 'Julius is a lion' 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
  0.75::factA.
  0.8::factB.
  0.0::factC.
  %hop1
  0.9::factX:-xor(factC,factA).
  0.25::factY:-or(factA,factC).
  0.7::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Greg is a frog' or 'Julius is a lion' or both.