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On the sum of squares of degrees and products of adjacent degrees. (English) Zbl 1329.05071
Summary: The sum of the squares of the degrees of vertices and the sum of the products of degrees of adjacent vertices have been introduced as topological indices. They are of interest from both applied and pure mathematical points of view. Given their close relations and rather similar behaviors, we examine the difference between these two indices in this note, presenting extremal results as well as some interesting properties.

##### MSC:
 05C07 Vertex degrees 05C05 Trees 05C10 Planar graphs; geometric and topological aspects of graph theory
##### Keywords:
Zagreb index; difference
Full Text:
##### References:
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