There is a better than even chance that Bernhard is a frog. It is probable that Mary went to the office. There is a very good chance that Brian is gray. Chances are slight that if 'Mary went to the office' or 'Brian is gray' or both then Sandra got the milk. There is a very good chance that if 'Mary went to the office' or 'Brian is gray' or both then Daniel left the apple. It is highly unlikely that if either 'Bernhard is a frog' or 'Brian is gray' but not both then Greg is a rhino.
It is highly likely that 'Daniel left the apple' or 'Brian is gray' or both.
It is highly likely that 'Daniel left the apple' or 'Brian is gray' or both.
It is probably not the case that 'Daniel left the apple' or 'Brian is gray' 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
  0.6::factA.
  0.7::factB.
  0.8::factC.
  %hop1
  0.1::factX:-or(factB,factC).
  0.8::factY:-or(factB,factC).
  0.05::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Daniel left the apple' or 'Brian is gray' or both.