We believe that John moved to the office. There is a better than even chance that Fred dropped the apple. Chances are about even that Brian is a lion. It is unlikely that if either 'Brian is a lion' or 'John moved to the office' but not both then Julius is yellow. Chances are slight that if 'Fred dropped the apple' or 'John moved to the office' or both then Gertrude is a sheep. There is a very good chance that if 'Fred dropped the apple and John moved to the office' then Lily is a swan.
It is probably the case that 'Brian is a lion and Gertrude is a sheep'.
It is highly unlikely that 'Brian is a lion and Gertrude is a sheep'.
It is probably the case that 'Brian is a lion and Gertrude is a sheep'.

  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.
  0.6::factB.
  0.5::factC.
  %hop1
  0.2::factX:-xor(factC,factA).
  0.1::factY:-or(factB,factA).
  0.8::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Brian is a lion and Gertrude is a sheep'.