There is a very good chance that Sandra got the football. It is unlikely that Jessica is a cat. It is likely that John went to the hallway. It is probably not the case that if 'Sandra got the football and John went to the hallway' then Brian is a rhino. There is almost no chance that if 'Jessica is a cat' or 'Sandra got the football' or both then Julius is yellow. It is probably not the case that if either 'Sandra got the football' or 'Jessica is a cat' but not both then Greg is a swan.
There is a very good chance that 'Sandra got the football' or 'Brian is a rhino' or both.
There is a very good chance that 'Sandra got the football' or 'Brian is a rhino' or both.
Chances are slight that 'Sandra got the football' or 'Brian is a rhino' 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.
  0.7::factC.
  %hop1
  0.25::factX:-and(factA,factC).
  0.02::factY:-or(factB,factA).
  0.25::factZ:-xor(factA,factB).

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

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