chromatic number problem sentence in Hindi

Examples

1. The chromatic number problem, also now known as the Hadwiger Nelson problem, was a favorite of Paul ErdQ
   s, who mentioned it frequently in his problems lectures.
2. Graph coloring has been studied as an algorithmic problem since the early 1970s : the chromatic number problem is one of Karp s 21 NP-complete problems from 1972, and at approximately the same time various exponential-time algorithms were developed based on backtracking and on the deletion-contraction recurrence of.