It is probable that Mary left the football. It is highly likely that Jessica is a sheep. Chances are about even that John moved to the office. It is improbable that if either 'Jessica is a sheep' or 'John moved to the office' but not both then Brian is a frog. There is little chance that if either 'Mary left the football' or 'Jessica is a sheep' but not both then Jeff went to the bedroom. Chances are about even that if 'Jessica is a sheep' or 'Mary left the football' or both then Bernhard is green.
Chances are about even that either 'Bernhard is green' or 'Jessica is a sheep' but not both.
Chances are about even that either 'Bernhard is green' or 'Jessica is a sheep' but not both.
It is highly unlikely that either 'Bernhard is green' or 'Jessica is a sheep' 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.
  0.5::factC.
  %hop1
  0.1::factX:-xor(factB,factC).
  0.1::factY:-xor(factA,factB).
  0.5::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Bernhard is green' or 'Jessica is a sheep' but not both.