It is probably the case that Brian is a lion. There is little chance that John took the apple. It is probably not the case that Fred is in the school. There is a very good chance that if 'Fred is in the school and Brian is a lion' then Lily is yellow. It is highly likely that if 'John took the apple' or 'Brian is a lion' or both then Greg is a swan. There is almost no chance that if either 'Brian is a lion' or 'John took the apple' but not both then Julius is a frog.
It is highly likely that 'Julius is a frog' or 'Fred is in the school' or both.
It is probably not the case that 'Julius is a frog' or 'Fred is in the school' or both.
It is highly likely that 'Julius is a frog' or 'Fred is in the school' 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
  0.7::factA.
  0.1::factB.
  0.25::factC.
  %hop1
  0.8::factX:-and(factC,factA).
  0.9::factY:-or(factB,factA).
  0.02::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Julius is a frog' or 'Fred is in the school' or both.