It is probable that Lily is a rhino. It is highly likely that Gertrude is a mouse. It is almost certain that John took the football. It is unlikely that if either 'John took the football' or 'Gertrude is a mouse' but not both then Greg is white. It is probably not the case that if 'John took the football and Lily is a rhino' then Mary went to the kitchen. It is probably not the case that if 'John took the football' or 'Lily is a rhino' or both then Bernhard is a lion.
Chances are about even that either 'Mary went to the kitchen' or 'Lily is a rhino' but not both.
Chances are about even that either 'Mary went to the kitchen' or 'Lily is a rhino' but not both.
There is almost no chance that either 'Mary went to the kitchen' or 'Lily is a rhino' 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
  0.7::factA.
  0.9::factB.
  0.95::factC.
  %hop1
  0.2::factX:-xor(factC,factB).
  0.25::factY:-and(factC,factA).
  0.25::factZ:-or(factC,factA).

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

  query(conclusion).
  
Either 'Mary went to the kitchen' or 'Lily is a rhino' but not both.