We doubt that Greg is a frog. It is likely that John discarded the apple. It is highly unlikely that Winona is a mouse. It is unlikely that if 'Winona is a mouse' or 'John discarded the apple' or both then Brian is a swan. It is probably not the case that if 'Winona is a mouse and Greg is a frog' then Julius is a swan. We believe that if 'Greg is a frog' or 'Winona is a mouse' or both then Bernhard is a lion.
There is almost no chance that 'Greg is a frog and Winona is a mouse'.
There is almost no chance that 'Greg is a frog and Winona is a mouse'.
We believe that 'Greg is a frog and Winona is a mouse'.

  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.
  0.7::factB.
  0.05::factC.
  %hop1
  0.2::factX:-or(factC,factB).
  0.25::factY:-and(factC,factA).
  0.75::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Greg is a frog and Winona is a mouse'.