We doubt that Emily is a sheep. It is highly likely that Sandra grabbed the apple. There is almost no chance that Brian is white. There is a very good chance that if 'Brian is white and Sandra grabbed the apple' then Mary got the football. It is almost certain that if either 'Emily is a sheep' or 'Brian is white' but not both then Greg is white. It is impossible that if either 'Emily is a sheep' or 'Sandra grabbed the apple' but not both then Bill went to the office.
It is unlikely that 'Greg is white' or 'Bill went to the office' or both.
It is unlikely that 'Greg is white' or 'Bill went to the office' or both.
It is almost certain that 'Greg is white' or 'Bill went to the office' 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
  0.2::factA.
  0.9::factB.
  0.02::factC.
  %hop1
  0.8::factX:-and(factC,factB).
  0.95::factY:-xor(factA,factC).
  0.0::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Greg is white' or 'Bill went to the office' or both.