There is a better than even chance that Mary went to the garden. There is almost no chance that Greg is a swan. There is a better than even chance that Brian is yellow. It is unlikely that if 'Mary went to the garden and Greg is a swan' then John took the apple. It is probably the case that if 'Brian is yellow' or 'Greg is a swan' or both then Julius is a lion. There is a very good chance that if 'Greg is a swan and Mary went to the garden' then Gertrude is a sheep.
There is almost no chance that 'John took the apple' or 'Gertrude is a sheep' or both.
There is almost no chance that 'John took the apple' or 'Gertrude is a sheep' or both.
It is probable that 'John took the apple' or 'Gertrude is a sheep' 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
  0.6::factA.
  0.02::factB.
  0.6::factC.
  %hop1
  0.2::factX:-and(factA,factB).
  0.7::factY:-or(factC,factB).
  0.8::factZ:-and(factB,factA).

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

  query(conclusion).
  
'John took the apple' or 'Gertrude is a sheep' or both.