It is highly unlikely that Emily is a mouse. Chances are about even that John went to the hallway. There is a very good chance that Jeff left the apple. It is almost certain that if either 'Jeff left the apple' or 'Emily is a mouse' but not both then Brian is white. It is unlikely that if 'Jeff left the apple' or 'John went to the hallway' or both then Sumit is tired. There is a better than even chance that if 'John went to the hallway and Jeff left the apple' then Jessica is a sheep.
It is probably not the case that 'Brian is white' or 'Jessica is a sheep' or both.
We believe that 'Brian is white' or 'Jessica is a sheep' or both.
It is probably not the case that 'Brian is white' or 'Jessica is a sheep' 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
  0.05::factA.
  0.5::factB.
  0.8::factC.
  %hop1
  0.95::factX:-xor(factC,factA).
  0.2::factY:-or(factC,factB).
  0.6::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Brian is white' or 'Jessica is a sheep' or both.