It is certain that Bill went to the kitchen. There is little chance that Brian is a frog. It is certain that John picked up the milk. There is a better than even chance that if 'Bill went to the kitchen' or 'John picked up the milk' or both then Lily is white. It is highly unlikely that if 'Brian is a frog and Bill went to the kitchen' then Fred is in the school. It is highly unlikely that if either 'Bill went to the kitchen' or 'Brian is a frog' but not both then Jeff dropped the apple.
It is likely that 'Fred is in the school and Bill went to the kitchen'.
It is impossible that 'Fred is in the school and Bill went to the kitchen'.
It is likely that 'Fred is in the school and Bill 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
  1.0::factA.
  0.1::factB.
  1.0::factC.
  %hop1
  0.6::factX:-or(factA,factC).
  0.05::factY:-and(factB,factA).
  0.05::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Fred is in the school and Bill went to the kitchen'.