TY - JOUR TI - On the sum-connectivity index AU - Wang Shilin AU - Bo Zhou AU - Trinajstić Nenad JN - Filomat PY - 2011 VL - 25 IS - 3 SP - 29 EP - 42 PT- Article AB- The sum-connectivity index of a simple graph G is defined in mathematical chemistry as R+(G) = ∑ uvєE(G)(du+dv)−1/2, where E(G) is the edge set of G and du is the degree of vertex u in G. We give a best possible lower bound for the sum-connectivity index of a graph (a triangle-free graph, respectively) with n vertices and minimum degree at least two and characterize the extremal graphs, where n ≥ 11.