It is highly unlikely that Bernhard is a rhino. Chances are about even that Winona is a wolf. We doubt that John left the football. Chances are about even that if 'John left the football and Winona is a wolf' then Greg is a frog. It is probably not the case that if either 'Winona is a wolf' or 'John left the football' but not both then Emily is a mouse. It is almost certain that if 'John left the football and Winona is a wolf' then Jeff went to the garden.
Chances are about even that 'Bernhard is a rhino' or 'Winona is a wolf' or both.
Chances are about even that 'Bernhard is a rhino' or 'Winona is a wolf' or both.
It is highly unlikely that 'Bernhard is a rhino' or 'Winona is a wolf' 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.
  0.5::factB.
  0.2::factC.
  %hop1
  0.5::factX:-and(factC,factB).
  0.25::factY:-xor(factB,factC).
  0.95::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Bernhard is a rhino' or 'Winona is a wolf' or both.