  We found that a second-order ideal memristor degenerates into a negative
nonlinear resistor. This phenomenon is quite similar to what are observed in
chemistry: a chemical element with a higher atomic number is unstable and may
decay radioactively into another chemical element with a lower atomic number.
After extending the above local activity (verified both graphically and
analytically) to other higher-order circuit elements, we concluded that all
higher-order passive memory circuit elements do not exist in nature and that
the periodic table of the two-terminal passive circuit elements can be
dramatically reduced to a six-pointed star comprising only six passive
elements. Such a bounded table may mark the end of the hunt for missing
higher-order passive circuit elements predicted nearly 40 years ago.
