It is probable that Bill moved to the office. There is little chance that Gertrude is a mouse. It is probably not the case that Fred dropped the apple. It is highly likely that if 'Bill moved to the office and Fred dropped the apple' then John went to the hallway. There is a better than even chance that if 'Bill moved to the office' or 'Gertrude is a mouse' or both then Julius is a swan. There is a better than even chance that if 'Gertrude is a mouse' or 'Fred dropped the apple' or both then Brian is a rhino.
We doubt that 'Fred dropped the apple and Bill moved to the office'.
We doubt that 'Fred dropped the apple and Bill moved to the office'.
It is probable that 'Fred dropped the apple and Bill moved to the office'.

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

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

  query(conclusion).
  
'Fred dropped the apple and Bill moved to the office'.