Which of the following languages is/are regular?
1
L1: {\(wxw^R| w, x \varepsilon\text{ {a, b}*}\) and |w|, |x| > 0}, \(w^R\) is the reverse of string w
2
L2 {wwR | w ϵ L}
3
L3: {ap bq cr) | p, q, r ≥ 0}
4
Prefix (L4) = {x ϵ ∑* | ∃x ϵ ∑* such that xy ϵ L4}