Is it possible to design a switch circuit with XNOR's truth table value?
In this position the lamp will be on. Switch A to the down position and the lamp will be off. Switch B to the down position and the lamp goes on again. So the lamp will be on if both switches are in the same position:

A     B     Lamp
up    up    on
up    down  off
down  up    off
down  down  on


This is equivalent to the XNOR's thruth table:

A     B     Y
0     0     1
0     1     0
1     0     0
1     1     1


To extend this circuit to more switches you need a "cross switch" (not sure about the name, in Dutch it's "kruisschakelaar"):



Changing the position of any switch will change the lamp's state, which is what you want if you want to control the lights in your living room from 2 or more points.