6. Determine whether each of the following sets on the alphabet {0,1} is regular or not. Provide a few sample strings for every set and justify your answer. [35=15] (a) the set consisting of those strings that contain, for all k,k1 's and k+10 's (b) the set of strings in which every 0 is immediately preceded by at least k1 's and is immediately followed by exactly k ''s, where k is a specified integer (c) the set of strings that contain more 1's than 0's (d) the set of strings consisting of a block of k20 's immediately followed by a single 1 , where k=0,1,2