Table 6.

The bidirectional extraction.

Variables	Reachability set	Antecedent set	Intersection set	Level
(a):Iteration-1
$c_1$	1	1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16	1	1
$c_2$	1,2,3,4,5,10	2,11,12,13,15	2
$c_3$	1,3,5	2,3,11,12,13,15,16	3
$c_4$	1,4	2,4,11,12,13,15	4
$c_5$	1,5	2,3,5,11,12,13,15,16	5
$c_6$	1,6	6,9,12,13,15,16	6
$c_7$	1,7	7,11,12,13,15	7
$c_8$	1,8	8,12,13,15	8
$c_9$	1,6,9	9,12,13,15	9
$c_{10}$	1,10	2,10,11,12,13,15	10
$c_{11}$	1,2,3,4,5,7,10,11	11	11
$c_{12}$	1,2,3,4,5,6,7,8,9,10,12,13,14,15,16	12	12
$c_{13}$	1,2,3,4,5,6,7,8,9,10,13	12,13	13
$c_{14}$	1,14	12,14	14
$c_{15}$	1,2,3,4,5,6,7,8,9,10,13,15	12,13,15	13,15
$c_{16}$	1,3,5,6,16	12,16	16
(b):Iteration-2
$c_2$	2,3,4,5,10	2,11,12,13,15,16	2
$c_3$	3,5	2,3,11,12,13,15,16	3
$c_4$	4	2,4,11,12,13,15	4
$c_5$	5	2,3,5,11,12,13,15,16	5
$c_6$	6	6,9,12,13,15,16	6
$c_7$	7	7,11,12,13,15	7
$c_8$	8	8,12,13,15	8
$c_9$	6,9	9,12,13,15	9
$c_{10}$	10	2,10,11,12,13,15	10
$c_{11}$	2,3,4,5,7,10,11	11	11	II
$c_{12}$	2,3,4,5,6,7,8,9,10,12,13,14,15,16	12	12	II
$c_{13}$	2,3,4,5,6,7,8,9,10,13	12,13	13
$c_{14}$	14	12,14	14
$c_{15}$	2,3,4,5,6,7,8,9,10,13,15	12,13,15	13,15
$c_{16}$	3,5,6,16	12,16	16
(c):Iteration-3
$c_2$	2,3,4,5,10	2, 13,15,16	2
$c_3$	3,5	2,3,13,15,16	3
$c_4$	4	2,4,,13,15	4	III
$c_5$	5	2,3,5,13,15,16	5	III
$c_6$	6	6,9,,13,15,16	6	III
$c_7$	7	7,13,15	7	III
$c_8$	8	8,13,15	8	III
$c_9$	6,9	9,13,15	9
$c_{10}$	10	2,10,13,15	10	III
$c_{13}$	2,3,4,5,6,7,8,9,10,13	13	13
$c_{14}$	14	14	14	III
$c_{15}$	2,3,4,5,6,7,8,9,10,13	13,15	13
$c_{16}$	3,5,6,16	16	16
(d):Iteration-4
$c_2$	2,3,	2,13,15,16	2
$c_3$	3,	2,3,13,15,16	3
$c_9$	9	9,13,15	9
$c_{13}$	2,3,9,13	13	13	IV
$c_{15}$	2,3,9,13,15	13,15	13,15	IV
$c_{16}$	3, 16	16	16	IV
(e):Iteration-5
$c_2$	2,3,	2	2
$c_3$	3,	2,3,	3	V
$c_9$	9	9,	9	V
(f):Iteration-6
$c_2$	2	2	2	VI