It is almost certain that John left the apple. It is unlikely that Julius is yellow. It is highly unlikely that Greg is a swan. It is probable that if either 'Julius is yellow' or 'John left the apple' but not both then Brian is a frog. It is highly unlikely that if 'John left the apple' or 'Julius is yellow' or both then Jason is tired. It is likely that if 'John left the apple and Julius is yellow' then Mary moved to the office.
It is probably not the case that 'Julius is yellow' or 'Jason is tired' or both.
It is probably not the case that 'Julius is yellow' or 'Jason is tired' or both.
We believe that 'Julius is yellow' or 'Jason is tired' 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
  0.95::factA.
  0.2::factB.
  0.05::factC.
  %hop1
  0.7::factX:-xor(factB,factA).
  0.05::factY:-or(factA,factB).
  0.7::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Julius is yellow' or 'Jason is tired' or both.