It is unlikely that Mary went to the bedroom. It is probable that Bernhard is yellow. It is probably the case that Brian is a lion. Chances are slight that if either 'Brian is a lion' or 'Mary went to the bedroom' but not both then Greg is white. It is probably the case that if either 'Brian is a lion' or 'Bernhard is yellow' but not both then John moved to the garden. It is probably the case that if 'Mary went to the bedroom' or 'Bernhard is yellow' or both then Sandra dropped the apple.
We believe that 'Mary went to the bedroom' or 'Bernhard is yellow' or both.
We believe that 'Mary went to the bedroom' or 'Bernhard is yellow' or both.
It is improbable that 'Mary went to the bedroom' or 'Bernhard is yellow' or both.

  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
  0.1::factX:-xor(factC,factA).
  0.7::factY:-xor(factC,factB).
  0.7::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Mary went to the bedroom' or 'Bernhard is yellow' or both.