# Identify the Class of a Given Language | Some Important Language – TOC

Here is the list of some language class you should know.

Language Class
CSL
CSL
CFL
DCFL
CSL
CFL
Regular
CSL
Regular
Regular
Regular
Regular
+ CSL
Regular
CSL
CFL

1. Pavan Shetty says:

Can anyone give reason why L={wxw∣w,x∈(a+b)∗} is Regular and L={xww∣w,x∈(a+b)∗} is Regular

1. Hi ,
Just put w as Epsilon in both of ur exmple … You will be Left with just c now c can be (a+b)* i.e it is covering all cases . But if there was + instead of * then it would be CSL

1. Pavan Shetty says:

You mean if x ∈ (a+b)* then lang. is RL and if x ∈ (a+b)+ is CSL ?

1. Yes for this Question .
If say L= wwwwwwwwwwwwwx , w,x∈(a+b)∗ Even in this case put w as epsilon , you will left with just x and it can expand as (a+b)* … so it is also regular

1. Pavan Shetty says:

Thank you I agree with your answer