A groups of 1s or 0s whose all members are overlapped by other groups is called redundant group. We don’t consider this group while writing the simplified equations from the K-map.

In the above K-map the group which is represented by the oval is a redundant group and hence while writing the equations we ignore it or we don’t make this kind of group and the K-map representation becomes as given next:

The equation we get is

F= yz’w’ + x’z’w (ignoring the redundant group)

If we consider this group then equation would be F= yz’w’ + x’z’w + x’yz’

And this is a not the simplified expression and hence **WRONG**.

K-map without the redundant group is: