It is highly unlikely that Sandra put down the milk. It is probably the case that Bernhard is a frog. Chances are about even that Brian is yellow. It is probable that if either 'Bernhard is a frog' or 'Brian is yellow' but not both then Lily is white. It is probably not the case that if either 'Sandra put down the milk' or 'Bernhard is a frog' but not both then Greg is a rhino. It is improbable that if 'Brian is yellow and Sandra put down the milk' then Mary went to the office.
It is almost certain that 'Brian is yellow and Greg is a rhino'.
There is little chance that 'Brian is yellow and Greg is a rhino'.
It is almost certain that 'Brian is yellow and Greg is a rhino'.

  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.
  0.7::factB.
  0.5::factC.
  %hop1
  0.7::factX:-xor(factB,factC).
  0.25::factY:-xor(factA,factB).
  0.1::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Brian is yellow and Greg is a rhino'.