It is probably the case that Mary moved to the office. We believe that Jeff left the football. Chances are about even that Emily is a mouse. We doubt that if 'Jeff left the football and Mary moved to the office' then Jessica is a sheep. It is unlikely that if either 'Mary moved to the office' or 'Emily is a mouse' but not both then Fred discarded the apple. Chances are about even that if 'Jeff left the football and Emily is a mouse' then Julius is green.
It is highly unlikely that either 'Emily is a mouse' or 'Mary moved to the office' but not both.
Chances are about even that either 'Emily is a mouse' or 'Mary moved to the office' but not both.
It is highly unlikely that either 'Emily is a mouse' or 'Mary moved to the office' 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.
  0.75::factB.
  0.5::factC.
  %hop1
  0.2::factX:-and(factB,factA).
  0.2::factY:-xor(factA,factC).
  0.5::factZ:-and(factB,factC).

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

  query(conclusion).
  
Either 'Emily is a mouse' or 'Mary moved to the office' but not both.