regular expression

Question

find regular expression for  " set of all strings over {0,1} having at most one pair of 0's or at most one pair of 1's.

Answer 1

This question asking for at most one occurrence of 11 or at most one occurrence of 00.

so start with : 

 (∈+ 1 + 11) + (∈+0+00)

Now we have to build around it the combination of 1’s and 0’s that will prevent another occurrence of “11" or "00"

  So,Regular Expression should be =

(0+∈) (10)^* (∈+ 1 + 11) (01)^* (0+∈)+ (1+∈) (01)^*(∈+0+00) (10)* (1+∈)

Comments

I think your (0+10)* can give any number of oo. And (1+01)* can produce any number of 11.

Acc. to me ans should be,

R=(0+∈) (10)^* ( ∈ + 1 + 11 )(01)^*(0+∈) + (1 + ∈)(01)*(∈ + 0 + 00)(10)^*(1+∈).

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i think you are right.Thank You. 

Answer 2

eps + 0 + 1 +( 01)* +( 10 )* + (01)* 00 (10)* + (10)*11(01)*