We believe that Yann is bored. We doubt that Jeff left the football. We believe that John got the apple. There is little chance that if 'Jeff left the football' or 'Yann is bored' or both then Jessica is a cat. There is a better than even chance that if 'Yann is bored and John got the apple' then Winona is a mouse. It is likely that if either 'Yann is bored' or 'Jeff left the football' but not both then Bernhard is green.
There is a very good chance that 'John got the apple' or 'Jeff left the football' or both.
There is a very good chance that 'John got the apple' or 'Jeff left the football' or both.
It is probably not the case that 'John got the apple' or 'Jeff left the football' 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.
  0.2::factB.
  0.75::factC.
  %hop1
  0.1::factX:-or(factB,factA).
  0.6::factY:-and(factA,factC).
  0.7::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'John got the apple' or 'Jeff left the football' or both.