Chances are about even that Mary got the football. We doubt that Bernhard is a rhino. There is little chance that Julius is a frog. It is highly unlikely that if 'Bernhard is a rhino and Julius is a frog' then Emily is a cat. There is a very good chance that if 'Bernhard is a rhino' or 'Julius is a frog' or both then Greg is a frog. There is little chance that if 'Julius is a frog and Bernhard is a rhino' then John went to the office.
Chances are slight that 'Julius is a frog' or 'John went to the office' or both.
Chances are slight that 'Julius is a frog' or 'John went to the office' or both.
It is probable 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
  0.5::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.05::factX:-and(factB,factC).
  0.8::factY:-or(factB,factC).
  0.1::factZ:-and(factC,factB).

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

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