It is highly unlikely that Bernhard is white. Chances are slight that John went to the kitchen. It is probably not the case that Greg is a rhino. There is almost no chance that if either 'Bernhard is white' or 'Greg is a rhino' but not both then Sandra dropped the milk. There is little chance that if 'John went to the kitchen' or 'Greg is a rhino' or both then Brian is a frog. There is a better than even chance that if either 'John went to the kitchen' or 'Greg is a rhino' but not both then Fred left the football.
It is probable that 'Bernhard is white and Brian is a frog'.
It is impossible that 'Bernhard is white and Brian is a frog'.
It is probable that 'Bernhard is white and Brian 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
  0.05::factA.
  0.1::factB.
  0.25::factC.
  %hop1
  0.02::factX:-xor(factA,factC).
  0.1::factY:-or(factB,factC).
  0.6::factZ:-xor(factB,factC).

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

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