It is probable that Brian is gray. It is probable that Greg is a frog. It is highly likely that Winona is a sheep. There is little chance that if 'Greg is a frog' or 'Brian is gray' or both then Jeff went to the garden. We doubt that if 'Brian is gray' or 'Winona is a sheep' or both then Julius is a swan. It is certain that if either 'Winona is a sheep' or 'Greg is a frog' but not both then Mary left the football.
It is almost certain that 'Julius is a swan and Mary left the football'.
It is highly unlikely that 'Julius is a swan and Mary left the football'.
It is almost certain that 'Julius is a swan and Mary left the football'.

  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
  0.7::factA.
  0.7::factB.
  0.9::factC.
  %hop1
  0.1::factX:-or(factB,factA).
  0.2::factY:-or(factA,factC).
  1.0::factZ:-xor(factC,factB).

  %hop2
  conclusion:-and(factY,factZ).

  query(conclusion).
  
'Julius is a swan and Mary left the football'.