There is little chance that John went to the office. It is certain that Julius is a frog. It is probably the case that Bernhard is a rhino. There is a better than even chance that if either 'Julius is a frog' or 'Bernhard is a rhino' but not both then Mary got the football. It is almost certain that if either 'Bernhard is a rhino' or 'Julius is a frog' but not both then Jeff left the apple. It is unlikely that if 'John went to the office and Bernhard is a rhino' then Gertrude is a cat.
It is certain that 'Julius is a frog' or 'John went to the office' or both.
It is certain that 'Julius is a frog' or 'John went to the office' or both.
There is little chance that 'Julius is a frog' or 'John 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
  0.1::factA.
  1.0::factB.
  0.7::factC.
  %hop1
  0.6::factX:-xor(factB,factC).
  0.95::factY:-xor(factC,factB).
  0.2::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Julius is a frog' or 'John went to the office' or both.