You have seven friends that you would like to invite to see

You have seven friends that you would like to invite to see your new home. However, certain pairs of your friends actually hate each other and it would not he good if they were both invited to your house on the same evening. The chart below shoves the pairs of friends that hate each other. For example, Alice hates Billy. Carl. Freddy, and Gina. What is the minimum number of evenings that are required in order to invite all of your six friend* to your hooch while insuring that you never invite two of your friends who hate each other on the same evening?

Solution

in the begining line it is given 7 friends and in the below it is 6 friends ? but when we observe that each of the 7 persons A<B<C<D<E<F<G< have only two friends with whom they can go . Suppose we invite AD one day we can invite EF other day , we can call BG the 3rd day and C on one day . Hence 4 days if there are 7 friends . one among A,B,C,D,E,F,G is host then it is 3 days