There is a very good chance that Mary took the football. It is highly likely that Bernhard is green. It is highly unlikely that Julius is gray. Chances are slight that if either 'Julius is gray' or 'Bernhard is green' but not both then Brian is white. It is highly likely that if 'Mary took the football and Julius is gray' then Lily is a lion. It is unlikely that if 'Bernhard is green and Julius is gray' then Greg is a frog.
Chances are slight that 'Greg is a frog' or 'Mary took the football' or both.
There is a very good chance that 'Greg is a frog' or 'Mary took the football' or both.
Chances are slight that 'Greg is a frog' or 'Mary took the football' 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
  0.8::factA.
  0.9::factB.
  0.05::factC.
  %hop1
  0.1::factX:-xor(factC,factB).
  0.9::factY:-and(factA,factC).
  0.2::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Greg is a frog' or 'Mary took the football' or both.