#TOC what does this statement means?

Question

input {0,1} Set of all strings that begin and end with either 0 or 1. What does this statement/line means and what would be the R.E for this?

Comments

it means string begin and end with either 0 or 1 which means (0+1)^+

Strings like 0,1,00,01,10,11,000,111,001............... All these string are either begin and end with either 0 or 1.

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@ Shubhanshu  You sure, bro!?

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It means for input symbols {0,1} set of all string that begins and ends with either 0 or set of all string that begins and ends with 1.

R.E.:- $(\ 1 \ (0+1)^{*} \ 1 \ \ + \ \ 0 \ (0+1)^{*} \ 0 \ )$

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@Shubhanshu Add it as answer, bro!

Answer 1

It means all the string that begin and end with same symbol, so the language generated will be 

{0,1,00,11,000........}.

The regular expression will be 

0(0+1)^*0 + 1(0+1)^*1

Comments

@LeenSharma @Rishabh Agrawal can 01 and 10 be a valid string? 

See this ques - https://gateoverflow.in/1307/gate2009-15 and see Arjun Sir's answer!

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@rahul sharma 5 Sir, can you pitch in?

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No,the question is all the string that begin and end with same symbol.

So 01 and 10 will be invalid.

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see this - https://gateoverflow.in/1307/gate2009-15 and read Praveen Saini's Answer!

Answer 2

it resides 2 answers

1)  ( 0(0+1)*1 + 1 (0+1)* 0)

2)  ( 1(0+1)*1 + 0 (0+1)* 0)