It is probably the case that Mary moved to the garden. Chances are slight that Gertrude is a sheep. It is probably the case that Brian is yellow. We doubt that if 'Gertrude is a sheep and Mary moved to the garden' then Lily is a swan. We doubt that if either 'Brian is yellow' or 'Gertrude is a sheep' but not both then John went to the hallway. It is highly unlikely that if 'Gertrude is a sheep' or 'Mary moved to the garden' or both then Julius is white.
We believe that 'Mary moved to the garden' or 'John went to the hallway' or both.
We believe that 'Mary moved to the garden' or 'John went to the hallway' or both.
We doubt that 'Mary moved to the garden' or 'John went to the hallway' 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.
  0.7::factC.
  %hop1
  0.2::factX:-and(factB,factA).
  0.2::factY:-xor(factC,factB).
  0.05::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Mary moved to the garden' or 'John went to the hallway' or both.