It is likely that Emily is a mouse. It is improbable that Sandra got the milk. There is a better than even chance that John went to the hallway. We believe that if 'John went to the hallway' or 'Sandra got the milk' or both then Mary moved to the garden. There is a better than even chance that if either 'Emily is a mouse' or 'Sandra got the milk' but not both then Brian is yellow. It is unlikely that if 'John went to the hallway and Emily is a mouse' then Julius is a swan.
There is almost no chance that 'John went to the hallway' or 'Brian is yellow' or both.
We believe that 'John went to the hallway' or 'Brian is yellow' or both.
There is almost no chance that 'John went to the hallway' or 'Brian 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
  0.7::factA.
  0.1::factB.
  0.6::factC.
  %hop1
  0.75::factX:-or(factC,factB).
  0.6::factY:-xor(factA,factB).
  0.2::factZ:-and(factC,factA).

  %hop2
  conclusion:-or(factC,factY).

  query(conclusion).
  
'John went to the hallway' or 'Brian is yellow' or both.