It is impossible that John picked up the apple. There is a better than even chance that Greg is a lion. It is highly unlikely that Brian is yellow. It is improbable that if 'Brian is yellow and John picked up the apple' then Lily is a rhino. We doubt that if 'John picked up the apple and Brian is yellow' then Bernhard is a frog. It is unlikely that if 'Greg is a lion and Brian is yellow' then Fred went to the office.
It is impossible that 'Brian is yellow and Bernhard is a frog'.
It is impossible that 'Brian is yellow and Bernhard is a frog'.
It is highly likely that 'Brian is yellow and Bernhard 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
  0.0::factA.
  0.6::factB.
  0.05::factC.
  %hop1
  0.1::factX:-and(factC,factA).
  0.2::factY:-and(factA,factC).
  0.2::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Brian is yellow and Bernhard is a frog'.