It is almost certain that Jason is tired. Chances are slight that Mary went to the kitchen. Chances are slight that Bernhard is a swan. It is impossible that if 'Jason is tired and Bernhard is a swan' then Brian is yellow. It is likely that if either 'Bernhard is a swan' or 'Jason is tired' but not both then Julius is a lion. We believe that if either 'Bernhard is a swan' or 'Mary went to the kitchen' but not both then Greg is a swan.
It is highly unlikely that 'Greg is a swan and Mary went to the kitchen'.
It is highly unlikely that 'Greg is a swan and Mary went to the kitchen'.
We believe that 'Greg is a swan and Mary went to the kitchen'.

  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.
  0.1::factB.
  0.1::factC.
  %hop1
  0.0::factX:-and(factA,factC).
  0.7::factY:-xor(factC,factA).
  0.75::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'Greg is a swan and Mary went to the kitchen'.