It is unlikely that Mary went to the bedroom. It is probable that John dropped the apple. It is probable that Julius is yellow. We believe that if 'John dropped the apple' or 'Julius is yellow' or both then Sandra left the milk. It is almost certain that if 'John dropped the apple and Mary went to the bedroom' then Brian is white. There is little chance that if either 'Mary went to the bedroom' or 'Julius is yellow' but not both then Greg is white.
It is almost certain that 'Mary went to the bedroom and Brian is white'.
Chances are slight that 'Mary went to the bedroom and Brian is white'.
It is almost certain that 'Mary went to the bedroom and Brian is white'.

  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
  0.2::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.75::factX:-or(factB,factC).
  0.95::factY:-and(factB,factA).
  0.1::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Mary went to the bedroom and Brian is white'.