We believe that Jessica is a mouse. It is likely that Lily is a rhino. It is probable that Yann is hungry. It is certain that if 'Jessica is a mouse' or 'Yann is hungry' or both then Brian is a swan. It is highly likely that if 'Lily is a rhino and Jessica is a mouse' then Emily is a wolf. It is unlikely that if 'Lily is a rhino and Yann is hungry' then Mary went to the garden.
There is little chance that either 'Mary went to the garden' or 'Jessica is a mouse' but not both.
It is probable that either 'Mary went to the garden' or 'Jessica is a mouse' but not both.
There is little chance that either 'Mary went to the garden' or 'Jessica is a mouse' 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
  0.75::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  1.0::factX:-or(factA,factC).
  0.9::factY:-and(factB,factA).
  0.2::factZ:-and(factB,factC).

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

  query(conclusion).
  
Either 'Mary went to the garden' or 'Jessica is a mouse' but not both.