It is highly unlikely that Lily is a frog. There is a very good chance that Greg is a frog. It is highly unlikely that Mary went to the garden. It is almost certain that if 'Greg is a frog' or 'Mary went to the garden' or both then Brian is a lion. Chances are slight that if 'Greg is a frog and Lily is a frog' then Yann is tired. It is improbable that if 'Mary went to the garden' or 'Greg is a frog' or both then Julius is a swan.
There is a very good chance that 'Greg is a frog' or 'Julius is a swan' or both.
There is a very good chance that 'Greg is a frog' or 'Julius is a swan' or both.
There is little chance that 'Greg is a frog' or 'Julius is a swan' 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
  0.05::factA.
  0.8::factB.
  0.05::factC.
  %hop1
  0.95::factX:-or(factB,factC).
  0.1::factY:-and(factB,factA).
  0.1::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Greg is a frog' or 'Julius is a swan' or both.