See,

number of (110)=number of (011)

if x=110 and y=001

or number of (x)=number of (y) .// Here it is 1 comparision,so we need a stack to do it.

So, it cannot be regular

secondly,

Regular expression is -:

L={0∗+1∗**+ **((ε+0+1)(ε+0+1))**+**0∗(0110)∗0∗ **+**1∗(11011)∗1∗} is not correct

{ε + 1 **+**( ( 1) ( 0 ) **+ ** ε **+** ε } = 110

**i.e (number of (110) !=number of (011)**

i.e : 110 or ... we can generate many strings which are **not in original L **