It is highly likely that Brian is a rhino. It is probably the case that Greg is white. Chances are about even that John went to the hallway. It is probable that if 'Brian is a rhino and Greg is white' then Julius is yellow. It is unlikely that if either 'John went to the hallway' or 'Greg is white' but not both then Lily is a swan. It is highly likely that if either 'Greg is white' or 'John went to the hallway' but not both then Emily is a mouse.
It is probably not the case that 'Greg is white and Emily is a mouse'.
It is probably not the case that 'Greg is white and Emily is a mouse'.
We believe that 'Greg is white and Emily is a mouse'.

  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
  0.9::factA.
  0.7::factB.
  0.5::factC.
  %hop1
  0.7::factX:-and(factA,factB).
  0.2::factY:-xor(factC,factB).
  0.9::factZ:-xor(factB,factC).

  %hop2
  conclusion:-and(factB,factZ).

  query(conclusion).
  
'Greg is white and Emily is a mouse'.