It is highly likely that Bernhard is a swan. Chances are about even that Jessica is a cat. It is highly unlikely that Fred went to the garden. We doubt that if 'Fred went to the garden' or 'Jessica is a cat' or both then John moved to the office. It is highly unlikely that if 'Fred went to the garden and Bernhard is a swan' then Brian is a rhino. It is probably the case that if 'Bernhard is a swan and Jessica is a cat' then Emily is a sheep.
It is highly likely that 'Emily is a sheep' or 'Bernhard is a swan' or both.
It is highly likely that 'Emily is a sheep' or 'Bernhard is a swan' or both.
It is impossible that 'Emily is a sheep' or 'Bernhard is a swan' or 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
  0.9::factA.
  0.5::factB.
  0.05::factC.
  %hop1
  0.2::factX:-or(factC,factB).
  0.05::factY:-and(factC,factA).
  0.7::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Emily is a sheep' or 'Bernhard is a swan' or both.