It is probably the case that Mary went to the office. Chances are about even that Greg is a rhino. It is unlikely that Brian is a frog. It is highly unlikely that if either 'Brian is a frog' or 'Greg is a rhino' but not both then Emily is a wolf. It is certain that if 'Greg is a rhino and Brian is a frog' then Jessica is a mouse. There is almost no chance that if either 'Mary went to the office' or 'Greg is a rhino' but not both then Julius is a swan.
We doubt that 'Mary went to the office' or 'Brian is a frog' or both.
We believe that 'Mary went to the office' or 'Brian is a frog' or both.
We doubt that 'Mary went to the office' or 'Brian is a frog' 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
  0.7::factA.
  0.5::factB.
  0.2::factC.
  %hop1
  0.05::factX:-xor(factC,factB).
  1.0::factY:-and(factB,factC).
  0.02::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Mary went to the office' or 'Brian is a frog' or both.