It is probably the case that Greg is green. We doubt that Brian is a rhino. We believe that Julius is a frog. There is almost no chance that if 'Julius is a frog and Brian is a rhino' then Gertrude is a sheep. It is highly unlikely that if either 'Greg is green' or 'Brian is a rhino' but not both then Mary moved to the office. It is probable that if either 'Julius is a frog' or 'Greg is green' but not both then Daniel got the milk.
Chances are slight that 'Brian is a rhino and Julius is a frog'.
Chances are slight that 'Brian is a rhino and Julius is a frog'.
It is probably the case that 'Brian is a rhino and Julius is a frog'.

  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.
  0.2::factB.
  0.75::factC.
  %hop1
  0.02::factX:-and(factC,factB).
  0.05::factY:-xor(factA,factB).
  0.7::factZ:-xor(factC,factA).

  %hop2
  conclusion:-and(factB,factC).

  query(conclusion).
  
'Brian is a rhino and Julius is a frog'.