Lecture on Closure Properties of Regular Language
Content covered: 

<div class="tex2jax">Closure Properties of Regular Languages: Union, Intersection, Concatenation, Kleene Closure</div>

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Ashish Kumar Goyal @dashish 20 Jan 2017 07:16 pm

Will Laa(language starting with a and ending with a) also include symbol 'a'??

as the start and end is the same..

Obaid Khan @obaidkhan 23 Jan 2017 11:09 pm

A machine accepting 'a' can not be said to have first and last symbols as 'a' because

a can be considered as a language having one a.

Eg: E* a E*={a,_a_,_ _a_ _.....}

Simple a cannot be said to be the ending and starting symbol at the same time. When ever a machine is given with a string i consumes the symbol and for your string " a " it would be consumed by the first transition and there will not be any end symbol. 

Antonio Anastasio Bruto da Costa @antonio 24 Jan 2017 11:29 am

So let me clarify this. A language having the same start and end symbol can be of length one.  However,  under the assumption that the start and end symbols must be identical and must not be in the same position,  ie not the string is not of length one, then what you are saying is applicable. So I perhaps should have made the definition  of the language clearer.