It is highly likely that Gertrude is a cat. It is improbable that Bernhard is a swan. There is almost no chance that Brian is a lion. Chances are slight that if either 'Bernhard is a swan' or 'Gertrude is a cat' but not both then Winona is a sheep. Chances are slight that if 'Brian is a lion and Bernhard is a swan' then Greg is white. It is probably the case that if either 'Brian is a lion' or 'Gertrude is a cat' but not both then Mary moved to the garden.
It is highly unlikely that 'Winona is a sheep and Mary moved to the garden'.
It is highly unlikely that 'Winona is a sheep and Mary moved to the garden'.
There is a better than even chance that 'Winona is a sheep and Mary moved to the garden'.

  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
  0.9::factA.
  0.1::factB.
  0.02::factC.
  %hop1
  0.1::factX:-xor(factB,factA).
  0.1::factY:-and(factC,factB).
  0.7::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Winona is a sheep and Mary moved to the garden'.