It is probably not the case that Gertrude is a cat. It is unlikely that Winona is a sheep. There is little chance that Julius is a lion. It is probable that if 'Gertrude is a cat' or 'Winona is a sheep' or both then Greg is a swan. There is a very good chance that if either 'Gertrude is a cat' or 'Winona is a sheep' but not both then Mary went to the garden. It is almost certain that if either 'Julius is a lion' or 'Gertrude is a cat' but not both then Sumit is bored.
It is impossible that 'Sumit is bored' or 'Greg is a swan' or both.
Chances are about even that 'Sumit is bored' or 'Greg is a swan' or both.
It is impossible that 'Sumit is bored' or 'Greg 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
  0.25::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.7::factX:-or(factA,factB).
  0.8::factY:-xor(factA,factB).
  0.95::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Sumit is bored' or 'Greg is a swan' or both.