There is a very good chance that Sandra took the football. It is unlikely that Greg is a frog. It is certain that Brian is a rhino. It is unlikely that if 'Brian is a rhino and Greg is a frog' then Julius is white. It is probably the case that if 'Sandra took the football' or 'Greg is a frog' or both then Jason is thirsty. It is impossible that if 'Greg is a frog' or 'Sandra took the football' or both then John went to the bedroom.
We doubt that 'Brian is a rhino' or 'Sandra took the football' or both.
It is certain that 'Brian is a rhino' or 'Sandra took the football' or both.
We doubt that 'Brian is a rhino' or 'Sandra 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.
  0.2::factB.
  1.0::factC.
  %hop1
  0.2::factX:-and(factC,factB).
  0.7::factY:-or(factA,factB).
  0.0::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Brian is a rhino' or 'Sandra took the football' or both.