Chances are about even that John went to the hallway. It is highly unlikely that Bernhard is a rhino. It is probably the case that Mary left the apple. Chances are about even that if either 'Bernhard is a rhino' or 'John went to the hallway' but not both then Gertrude is a wolf. There is a better than even chance that if 'Bernhard is a rhino' or 'John went to the hallway' or both then Julius is a frog. Chances are about even that if 'Mary left the apple and Bernhard is a rhino' then Greg is a swan.
We doubt that 'Mary left the apple and Gertrude is a wolf'.
We doubt that 'Mary left the apple and Gertrude is a wolf'.
It is probable that 'Mary left the apple and Gertrude is a wolf'.

  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
  0.5::factA.
  0.05::factB.
  0.7::factC.
  %hop1
  0.5::factX:-xor(factB,factA).
  0.6::factY:-or(factB,factA).
  0.5::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Mary left the apple and Gertrude is a wolf'.