It is likely that Brian is a lion. It is probably the case that John put down the apple. There is almost no chance that Jeff discarded the milk. There is little chance that if 'Jeff discarded the milk and John put down the apple' then Mary got the milk. It is highly likely that if either 'Jeff discarded the milk' or 'John put down the apple' but not both then Bernhard is a swan. It is highly unlikely that if either 'Brian is a lion' or 'John put down the apple' but not both then Jessica is a sheep.
Chances are about even that 'Brian is a lion and Jeff discarded the milk'.
There is almost no chance that 'Brian is a lion and Jeff discarded the milk'.
Chances are about even that 'Brian is a lion and Jeff discarded the milk'.

  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
  0.7::factA.
  0.7::factB.
  0.02::factC.
  %hop1
  0.1::factX:-and(factC,factB).
  0.9::factY:-xor(factC,factB).
  0.05::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Brian is a lion and Jeff discarded the milk'.