It is improbable that Emily is a sheep. Chances are about even that Greg is a swan. Chances are about even that Brian is yellow. It is probable that if 'Greg is a swan and Emily is a sheep' then Bernhard is white. It is probable that if either 'Greg is a swan' or 'Emily is a sheep' but not both then Mary went to the kitchen. There is almost no chance that if either 'Greg is a swan' or 'Emily is a sheep' but not both then John took the apple.
It is highly likely that 'Emily is a sheep and Greg is a swan'.
It is highly unlikely that 'Emily is a sheep and Greg is a swan'.
It is highly likely that 'Emily is a sheep and Greg is a swan'.

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

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

  query(conclusion).
  
'Emily is a sheep and Greg is a swan'.