It is likely that John went to the bedroom. There is little chance that Gertrude is a mouse. It is impossible that Mary moved to the office. There is a very good chance that if 'John went to the bedroom and Mary moved to the office' then Lily is yellow. There is a better than even chance that if either 'John went to the bedroom' or 'Gertrude is a mouse' but not both then Jeff dropped the apple. It is certain that if either 'John went to the bedroom' or 'Mary moved to the office' but not both then Brian is a lion.
There is almost no chance that 'Jeff dropped the apple and Brian is a lion'.
Chances are about even that 'Jeff dropped the apple and Brian is a lion'.
There is almost no chance that 'Jeff dropped the apple and Brian is a lion'.

  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.
  0.1::factB.
  0.0::factC.
  %hop1
  0.8::factX:-and(factA,factC).
  0.6::factY:-xor(factA,factB).
  1.0::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Jeff dropped the apple and Brian is a lion'.