1. BACKTRACKING

2. STRUCTURE
» Introduction
» Rules
» Practice Questions

3. INTRODUCTION
» Way to make graph easily
» Use of 3 Basic Colors (R,G,B)
» Removing conflicts

4. RULES
» Restriction for using 3 colors
» No Conflict
» Back Track

5. Cont…
Color this graph:

6. Practice Question
i) Back Tracking:
A–R
A B
B–R B–G
D
C–R C–G C–B C
F
D–R D–G
E
E–R
F–B

7. Cont…
ii) Back Tracking:
E–R
B–B
A–R
F–R F–G B F
D–G
C–R C–B
E–B
F–G A D
F–R
F–B E
C – R C – BC – G
C
C–R C–B C–G

8. Cont…
iii) Back Tracking:
C–R E–B
A–R E D
F–R F–G
B–G
D–R D–B F
C–B
F–G G–B A B C
F–R
G
D – R D – BD – G
D–R D–B D–G F–B
D–R D–B D–G

9. Cont…
iv) Back Tracking:
D–R C–R
G–R G
B–R B–B
E–B
A–R A–G
D–G A E
B–G F–G F
B–R
B–B
C B D
A–R A– B A–G
A–R A–B A–G