It is certain that Brian is green. It is certain that Mary picked up the apple. It is improbable that John went to the office. There is a better than even chance that if 'Brian is green' or 'John went to the office' or both then Sandra left the milk. It is highly likely that if 'Mary picked up the apple' or 'John went to the office' or both then Greg is gray. There is little chance that if 'Mary picked up the apple' or 'John went to the office' or both then Lily is a rhino.
There is a better than even chance that 'Sandra left the milk and Mary picked up the apple'.
There is a better than even chance that 'Sandra left the milk and Mary picked up the apple'.
It is highly unlikely that 'Sandra left the milk and Mary picked up the apple'.

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

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

  query(conclusion).
  
'Sandra left the milk and Mary picked up the apple'.