Question

Give formal definition of the regular language generated by the following Regular Expressions:

1) ((ab*+a)*+ab)

2) (a+b)*c(a+b)*

3) (ab)*+a*b

Answer 1

Ans:

Given Expression:

Expression	Formal definition
((ab*+a)*+ab)	A language which accepts from a given Set of strings a,b where the generated string starts by a. Example: { a,ab,aab,aaaa,aaaaab,ab,ab,abbbbaba…}
(a+b)*c(a+b)*	A language which accepts from a given Set of strings a,b where the generated string starts must contain c as substring {c,acb,abcbc,aacbb,aacbb…….}
(ab)*+a*b	A language which accepts from a given Set of strings a,b where the generated string contains any length of consecutive a must followed by single b. Example: {b,ab,aab,abab,aabab..aaaabababa….} Note: {b, here consecutive a length =0 }