(*  Vérifier qu'un texte est un palindrome:  *)


let rec pal2(s) =
            if s = ""  or  string_length(s) = 1
            then true
            else
                if pr(s) <= `A`  &  pr(s) >= `Z`
                then pal2(char_of_int(int_of_char(pr(s)) + 32))
                else
                    if dr(s) <= `A`  &  dr(s) >= `Z`
                    then pal2(char_of_int(int_of_char(dr(s)) + 32))
                    else
                        if pr(s) = ` `  or  pr(s) = `'`  or  pr(s) = `-`  or   pr(s) = `_`  or  pr(s) = `,`
                        then pal2(sp(s))
                        else
                            if  dr(s) = ` `  or  dr(s) = `'`  or  dr(s) = `-`  or   dr(s) = `_`  or dr(s) = `,`
                            then pal2(sd(s))
                            else
                                if pr(s) = dr(s)
                                then pal2(sp(sd(s)))
                                else false;;