Chances are slight that Lily is a lion. It is highly unlikely that John dropped the milk. There is a better than even chance that Sumit is bored. It is unlikely that if either 'John dropped the milk' or 'Sumit is bored' but not both then Brian is green. It is certain that if 'John dropped the milk and Lily is a lion' then Julius is a swan. It is probable that if 'Lily is a lion' or 'John dropped the milk' or both then Mary went to the kitchen.
We believe that 'Brian is green and Sumit is bored'.
There is little chance that 'Brian is green and Sumit is bored'.
We believe that 'Brian is green and Sumit is bored'.

  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.
  0.05::factB.
  0.6::factC.
  %hop1
  0.2::factX:-xor(factB,factC).
  1.0::factY:-and(factB,factA).
  0.7::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Brian is green and Sumit is bored'.