There is little chance that Fred left the football. It is probably the case that Bernhard is a swan. It is almost certain that John picked up the apple. There is a better than even chance that if 'Fred left the football' or 'John picked up the apple' or both then Mary moved to the garden. We believe that if 'Bernhard is a swan' or 'Fred left the football' or both then Brian is white. It is impossible that if either 'Bernhard is a swan' or 'Fred left the football' but not both then Greg is a frog.
It is almost certain that 'Fred left the football and Brian is white'.
Chances are slight that 'Fred left the football and Brian is white'.
It is almost certain that 'Fred left the football and Brian is white'.

  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
  0.1::factA.
  0.7::factB.
  0.95::factC.
  %hop1
  0.6::factX:-or(factA,factC).
  0.75::factY:-or(factB,factA).
  0.0::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Fred left the football and Brian is white'.