graph theory ,discrete math

Question

how many subgraph with atleast 1 vertex does k2 have?  (graph theory question)

Comments

yes it should be 3 bcoz nothing is given about uniqueness

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why haven't you considered null graph with 2 vertices in both cases?

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I think you are correct we should add +1 for each labelled and unlabelled case.

Answer 1

ithink this formula should be better gor this type of solution

 

$_{1}^{2}\textrm{c}$*2^n(n-1)/2