We believe that Sumit is hungry. It is likely that Julius is a rhino. It is certain that Greg is white. There is a better than even chance that if either 'Greg is white' or 'Sumit is hungry' but not both then Mary went to the hallway. We doubt that if 'Greg is white and Sumit is hungry' then Fred discarded the apple. There is almost no chance that if 'Julius is a rhino' or 'Sumit is hungry' or both then Jason is tired.
Chances are about even that 'Greg is white' or 'Fred discarded the apple' or both.
It is certain that 'Greg is white' or 'Fred discarded the apple' or both.
Chances are about even that 'Greg is white' or 'Fred 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
  0.75::factA.
  0.7::factB.
  1.0::factC.
  %hop1
  0.6::factX:-xor(factC,factA).
  0.2::factY:-and(factC,factA).
  0.02::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Greg is white' or 'Fred discarded the apple' or both.