Question

please help me in defining the language of strings of length 3over "sigma"={#,%,@}
b) reverse of it
c)if any palindrome identify

Answer 1

a) \(L=\{x \in \{\#, \%, @\}^* : |x| > 3\}\)
b) \(\overline{L}=\{x \in \Sigma^* : x \not\in L\}\)

Let \(PAL\) be the language accepted by the following CFG:
S \(\to\) #S#
S \(\to\) %S%
S \(\to\) @S@
S \(\to\varepsilon\)

Answer 2

good answer, but two things...
to make this problem tractable the string length is 3 |x|=3
and %@% @#@ ### #%# are palindromes

going to need one more state, but it's almost there

Answer 3

how to get palindrome?

Answer 4

the language consisting of null string and rev(s)=s are the two specific conditions for palindrome so how can we get palindrome in this language as its strings dose not consists of null string
sigma -{#%@}

Answer 5

for all palindromes length 3, how about
S → #A#
S → %A%
S → @A@
A → #
A → %
A → @