We believe that Sandra dropped the milk. Chances are slight that Mary got the football. It is probably the case that John put down the apple. It is highly likely that if either 'Sandra dropped the milk' or 'Mary got the football' but not both then Jeff moved to the office. It is highly unlikely that if 'Mary got the football and John put down the apple' then Greg is a lion. It is probable that if 'Sandra dropped the milk and Mary got the football' then Brian is white.
There is little chance that 'John put down the apple' or 'Jeff moved to the office' or both.
It is highly likely that 'John put down the apple' or 'Jeff moved to the office' or both.
There is little chance that 'John put down the apple' or 'Jeff 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
  0.75::factA.
  0.1::factB.
  0.7::factC.
  %hop1
  0.9::factX:-xor(factA,factB).
  0.05::factY:-and(factB,factC).
  0.7::factZ:-and(factA,factB).

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

  query(conclusion).
  
'John put down the apple' or 'Jeff moved to the office' or both.