3. The following is a grammar for regular expressions over symbols a and b only. using + for union, to avoid conflict with the use of vertical bar as a meta-symbol in grammars: rexpr rexpr + rterm | rterm rterm rterm rfactor | rfactor rfactor rfactor rprimary rprimary HS a l b a) Left factor this grammar b) Does left factoring make the grammar suitable for top-down parsing? c) In addition to left factoring, eliminate left recursion from the original grammar. d) Is the resulting grammar suitable for top-down parsing? Repeat above exercise 3 for the following grammars: 2) S > es1 101