We doubt that Mary left the football. It is impossible that Greg is white. It is impossible that John moved to the office. It is certain that if 'Mary left the football and Greg is white' then Yann is hungry. There is little chance that if 'Greg is white and Mary left the football' then Emily is a mouse. It is almost certain that if either 'Greg is white' or 'John moved to the office' but not both then Bill got the milk there.
It is highly likely that 'Emily is a mouse' or 'John moved to the office' or both.
It is impossible that 'Emily is a mouse' or 'John moved to the office' or both.
It is highly likely that 'Emily is a mouse' or 'John moved to the office' or both.

  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
  0.2::factA.
  0.0::factB.
  0.0::factC.
  %hop1
  1.0::factX:-and(factA,factB).
  0.1::factY:-and(factB,factA).
  0.95::factZ:-xor(factB,factC).

  %hop2
  conclusion:-or(factY,factC).

  query(conclusion).
  
'Emily is a mouse' or 'John moved to the office' or both.