Chances are about even that Lily is a lion. It is highly likely that Greg is yellow. It is likely that Mary took the football. It is impossible that if 'Greg is yellow and Mary took the football' then Julius is a frog. We believe that if 'Greg is yellow' or 'Mary took the football' or both then Emily is a wolf. It is unlikely that if 'Greg is yellow and Lily is a lion' then Brian is a swan.
Chances are slight that 'Brian is a swan and Lily is a lion'.
Chances are slight that 'Brian is a swan and Lily is a lion'.
It is probably the case that 'Brian is a swan and Lily is a lion'.

  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
  0.5::factA.
  0.9::factB.
  0.7::factC.
  %hop1
  0.0::factX:-and(factB,factC).
  0.75::factY:-or(factB,factC).
  0.2::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Brian is a swan and Lily is a lion'.