There is a very good chance that Mary went to the bedroom. It is highly unlikely that Daniel took the football. There is little chance that Sandra got the milk. It is probably the case that if either 'Mary went to the bedroom' or 'Daniel took the football' but not both then Emily is a mouse. There is a better than even chance that if 'Daniel took the football and Sandra got the milk' then John put down the apple. It is highly likely that if either 'Mary went to the bedroom' or 'Daniel took the football' but not both then Julius is a lion.
It is unlikely that either 'Mary went to the bedroom' or 'Daniel took the football' but not both.
We believe that either 'Mary went to the bedroom' or 'Daniel took the football' but not both.
It is unlikely that either 'Mary went to the bedroom' or 'Daniel took the football' but not both.

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

  %hop2
  conclusion:-xor(factA,factB).

  query(conclusion).
  
Either 'Mary went to the bedroom' or 'Daniel took the football' but not both.