There is little chance that John left the milk. It is probably not the case that Greg is white. We doubt that Jeff moved to the office. It is probably the case that if 'Greg is white' or 'John left the milk' or both then Lily is a swan. It is unlikely that if either 'John left the milk' or 'Greg is white' but not both then Brian is a lion. It is probably not the case that if either 'John left the milk' or 'Greg is white' but not both then Mary got the football.
There is almost no chance that 'John left the milk and Brian is a lion'.
There is almost no chance that 'John left the milk and Brian is a lion'.
It is probably the case that 'John left the milk and Brian 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
  0.1::factA.
  0.25::factB.
  0.2::factC.
  %hop1
  0.7::factX:-or(factB,factA).
  0.2::factY:-xor(factA,factB).
  0.25::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'John left the milk and Brian is a lion'.