On Chemical Trees That Maximize Atom–Bond Connectivity Index, Its Exponential Version, and Minimize Exponential Geometric–Arithmetic Index

A chemical tree is a tree that has no vertex of degree greater than 4. We denote the set of chemical trees with n vertices as Cn. The ABC index of a chemical tree T is defined as ABC (T) = X 1≤i≤j≤4 mi,j (T) s i + j − 2 ij , where mi,j (T) is the number of edges in T joining vertices of degree i and...