It is impossible that Fred went to the office. It is improbable that Gertrude is a mouse. It is unlikely that Julius is a frog. We doubt that if 'Gertrude is a mouse and Julius is a frog' then John got the milk. It is probably not the case that if 'Fred went to the office and Gertrude is a mouse' then Brian is a rhino. We doubt that if 'Gertrude is a mouse and Fred went to the office' then Lily is a frog.
There is a very good chance that 'Julius is a frog' or 'Lily is a frog' or both.
We doubt that 'Julius is a frog' or 'Lily is a frog' or both.
There is a very good chance that 'Julius is a frog' or 'Lily is a frog' 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
  0.0::factA.
  0.1::factB.
  0.2::factC.
  %hop1
  0.2::factX:-and(factB,factC).
  0.25::factY:-and(factA,factB).
  0.2::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Julius is a frog' or 'Lily is a frog' or both.