There is a better than even chance that John went to the office. We doubt that Antoine is hungry. We believe that Brian is yellow. It is improbable that if either 'John went to the office' or 'Brian is yellow' but not both then Julius is a frog. Chances are about even that if either 'Antoine is hungry' or 'John went to the office' but not both then Gertrude is a mouse. There is a very good chance that if 'Antoine is hungry and Brian is yellow' then Sandra left the apple.
It is impossible that 'Sandra left the apple and Julius is a frog'.
It is impossible that 'Sandra left the apple and Julius is a frog'.
We believe that 'Sandra left the apple and Julius is a frog'.

  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
  0.6::factA.
  0.2::factB.
  0.75::factC.
  %hop1
  0.1::factX:-xor(factA,factC).
  0.5::factY:-xor(factB,factA).
  0.8::factZ:-and(factB,factC).

  %hop2
  conclusion:-and(factZ,factX).

  query(conclusion).
  
'Sandra left the apple and Julius is a frog'.