It is likely that Jessica is a mouse. There is a very good chance that Brian is white. It is highly likely that John went to the hallway. It is probable that if 'Brian is white' or 'Jessica is a mouse' or both then Bernhard is gray. It is highly likely that if 'John went to the hallway and Brian is white' then Greg is a rhino. It is probable that if 'Jessica is a mouse and John went to the hallway' then Mary dropped the apple.
There is a very good chance that 'Bernhard is gray' or 'Mary dropped the apple' or both.
There is a very good chance that 'Bernhard is gray' or 'Mary dropped the apple' or both.
Chances are slight that 'Bernhard is gray' or 'Mary dropped the apple' 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.
  0.8::factB.
  0.9::factC.
  %hop1
  0.7::factX:-or(factB,factA).
  0.9::factY:-and(factC,factB).
  0.7::factZ:-and(factA,factC).

  %hop2
  conclusion:-or(factX,factZ).

  query(conclusion).
  
'Bernhard is gray' or 'Mary dropped the apple' or both.