4. a. Most compiler parsers use a Bottom Up parsing technique. Can you explain why? [Give at least one good reason.]

b/ Augment the grammar below (add S). Build the START STATE and ANY OTHER 3 states.

1,2: S [ S X ] | a 3,4,5: X epsilon | + S Y | Y b 6,7: Y epsilon | - S X c

d Consider the grammar: 1. S qwS 2. S SzS, 3. S q, 4. S x with table below.

Using the table below, show the FIRST 6 moves on an SLR parse of the string: q z q w x $

	q	w	x	z	$	S
1	S2					3
2		S5		R3	R3
3				S6	ACC
4				R4	R4	8
5	S2	S4	S4
6	S2	S4
7				S6	R2
8				S6	R1