It is improbable that Greg is yellow. There is a very good chance that Mary went to the bedroom. It is likely that Bernhard is a swan. Chances are slight that if 'Bernhard is a swan' or 'Greg is yellow' or both then Brian is white. Chances are slight that if either 'Greg is yellow' or 'Bernhard is a swan' but not both then Sandra grabbed the apple. It is probably not the case that if 'Mary went to the bedroom and Bernhard is a swan' then Emily is a mouse.
It is likely that 'Brian is white and Emily is a mouse'.
There is almost no chance that 'Brian is white and Emily is a mouse'.
It is likely that 'Brian is white and Emily is a mouse'.

  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.
  0.8::factB.
  0.7::factC.
  %hop1
  0.1::factX:-or(factC,factA).
  0.1::factY:-xor(factA,factC).
  0.25::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Brian is white and Emily is a mouse'.