The energy of a graph G, is de fined as the sum of the absolute values of all eigenvalues of G. In this talk, we study the difference of energies of a (regular) graph G and its complete graph. In particular, we provide the answer to Problem 12 raised in [V. Nikiforov, Remarks on the energy of regular graphs, Linear Algebra Appl. 508 (2016) 133-145]. Moreover, we give a lower bound for the energy of a regular graph in terms of the order and the clique cover number.

Coffee and biscuits will be offered at the beginning of the seminar.
Welcome to everyone!