Topological graph theory and graphs of positive combinatorial curvature

This thesis considers the open problem in topological graph theory: What is the largest connected graph of minimum degree 3 which has everywhere positive combinatorial curvature but is not in one of the infinite families of graphs of positive combinatorial curvature? This problem involves the generalization of the notion of curvature (a geometric concept) to graphs (a combinatorial structure). The thesis presents past progress on the upper and lower bounds for this problem as well as graph operations that may be used in the future for improving the lower bound.