Chances are slight that Brian is yellow. There is a better than even chance that Mary left the football. Chances are slight that Bill went to the office. It is highly likely that if 'Bill went to the office and Mary left the football' then John put down the apple. It is highly unlikely that if either 'Mary left the football' or 'Brian is yellow' but not both then Greg is a rhino. It is certain that if 'Mary left the football and Brian is yellow' then Lily is yellow.
It is impossible that 'John put down the apple and Lily is yellow'.
It is impossible that 'John put down the apple and Lily is yellow'.
It is almost certain that 'John put down the apple and Lily is yellow'.

  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
  0.1::factA.
  0.6::factB.
  0.1::factC.
  %hop1
  0.9::factX:-and(factC,factB).
  0.05::factY:-xor(factB,factA).
  1.0::factZ:-and(factB,factA).

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

  query(conclusion).
  
'John put down the apple and Lily is yellow'.