Chances are about even that Bernhard is gray. It is impossible that Julius is green. It is impossible that Lily is a rhino. It is certain that if 'Julius is green and Bernhard is gray' then Jason is tired. It is probable that if either 'Lily is a rhino' or 'Bernhard is gray' but not both then John discarded the apple. It is highly likely that if 'Bernhard is gray and Julius is green' then Greg is a swan.
It is probably not the case that 'Greg is a swan' or 'John discarded the apple' or both.
It is probably not the case that 'Greg is a swan' or 'John discarded the apple' or both.
It is highly likely that 'Greg is a swan' or 'John discarded 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
  0.5::factA.
  0.0::factB.
  0.0::factC.
  %hop1
  1.0::factX:-and(factB,factA).
  0.7::factY:-xor(factC,factA).
  0.9::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Greg is a swan' or 'John discarded the apple' or both.